In regards to using OSB, I have the following comment: I am a structural engineer in California, and I have specified OSB as a subfloor, roof sheathing & shear wall sheathing for hundreds of homes. As far as an underlayment for hardwood floors, there appears to be two issues. 1) is the floor structurally sound for hardwood, and 2) whether attaching the hardwood directly to OSB will result in nail slippage many years down the road. I have comments on both issues. As far as the floor being structurally sound, I have seen a few posts on this issue & I am not one to automatically say that hardwood should be placed perpendicular to the floor joists... But it would definitely be stronger and may help in easily repairing the hardwood attachment if the nails should slip many years down the road. I myself have placed the hardwood parallel to the floor joist because my subfloor is very stiff. To get a stiff floor, this is my recommendations: joist spacing should not exceed 16"o.c.; floor joist span should be designed conservatively (building code minimum is not conservative), and floor sheathing should be 3/4" nominal and placed with the face grain (long dimension) perpendicular to the joist & staggered. In regards to item 2: some national floor associations have said direct OSB attachment is acceptable as long as sheathing is PS2 standard & 23/32" minimum. That is all we can go by. As I mentioned above, let's say the nails do slip after many years... If your hardwood is perpendicular to the joist, couldn't you just screw it down to the joist below as a repair? That is one benefit I can see with placing the hardwood perpendicular to the joist or adding blocking between the joist. In regards to nail slip, I posted a blog regarding using the hardwood nailers that drive the cleats at an angle in the tongue of the hardwood edge. The cleats are locked in place inside the T & G connection. How is this going to lift up? Also when you drive the nail at an angle, there is a vertical bearing component of the nail that is preventing the nails from lifting. This is versus using a brad nailer that goes vertical. The vertical nail would rely totally on friction between the OSB & nail and I can see this possibly slipping down the road.

To move the cooktop to the perimeter location involves: Removing the perimeter countertop, which may break. The reason you have to remove it is because the cooktop will not fit into the cabinets below where you want it to be. You have 2 cabinets there, not a single cooktop cabinet. So you will need to move the cooktop cabinet there and one of those cabinets to the island. However, that won't work for your already installed flooring unless it runs under the cabinets. Of course, you could have an expert cabinet maker demolish the interior of the two side supports of those cabinets and rebuild them with additional support and then just cut a hole in the granite in place. Not cheap, either way. You will have to have an expert cabinet person modify the upper cabinet above to be shorter, or build an entirely new one to be shorter. Yes, you could just move it up, but then it would look really strange. If you can live with that, that would be the cheapest solution for the upper cabinet. It will still need to have a hole cut into it for the vent pipe. You will also have to run either gas or 220 electric to that location. Gas has to be in rigid black iron pipe. Only the last few feet can be in flexible stainless. THe plumber will have to calculate if you can T off of the gas supply that (I hope) is running through the attic and not just through the slab foundation. That black iron has to be run down through that outside wall from the attic and into the cabinet below the cooktop location. If you did induction, you'd have a similar herculean run all the way from the electrical box. That means tearing up the drywall surface to run those things, and then repairing it. That's best case scenario and they can actually manage to get the pipe to run through the stud cavity and not down the outside of the house. Then you'd have to deal with running the electrical for the vent, and cutting the hole in your house for the vent. That involves patching the exterior siding and installing a damper. And that is even if your jurisdiction would allow a vent straight out the wall in that location. In most locations, it's too close to an operable window to allow termination there and would have to go through the roof. Taking it through the roof involves a big old pipe sticking up quite a ways. It has to, because of code requirements and it's location there on the eaves. And it involves a roof penetration, which needs someone who knows the heck what they're doing for you not to have a leak. Not rocket surgery, but you'd be surprised at how often a "handyman" will screw it up. It's something you need an HVAC trade for, and possibly a roofer. More expensive, but you tend to rule out the "and master of none" jacks. Then, you'd have to replace the island counter. THe suggested butcher block would be a good budget friendly surface that would work. If the Brazillian Brown Silestone on the perimeter cracks, you'd need to be OK with them glueing it back together, or replacing it. Replacing it would be 5-7K, and I didn't count that in the total here at the end. All in all, you'd be spending a minimum of 10K to move the cooktop off of the island. Probably more, because it's an older house, and once you start touching stuff like electrical, you've got to bring some things up to current codes. And you'd still be left with a barrier island with the critical to access fridge on the wrong side of it, and the ovens in an inconvenient spot. You'd be left with the dumping ground of the desk area. You'd be left prepping on top of your cleanup area in about 30" of space. Meaning you will have a one person kitchen. "Spacious" isn't spacious when all of the zones are overlapping and everyone needs to use the same exact square footage that you do, or you have to put on rollerskates to get from one side of the space to the other. It doesn't matter if the kitchen is 20x20 if all of the zones overlap at the sink and you have to always walk around an obstacle to perform even the simplest sandwich prep. As I said, the cheapest option at this point would be to do an overhead vent through the roof and then replace the island counter with one with more overhang. That would only cost you 4-5K or so. It would still leave the other issues that the kitchen has, and it would reduce your aisle way in front of the fridge, but it would get you through until you could address the rest of the issues in a more complete redo.

I agree that there is no need to remove the old sheet vinyl. You don't need to be concerned with any difference in height (that someone mentioned above) as one layer of sheet vinyl next to carpet won't amount to much at all. Certainly no difference worth noting. If your current floor does not appear to have any bumps or places that stand out as being uneven, and is a "flat" vinyl, then you should be good. The installer should know to check this out thoroughly - if they are any good. Also, if there is existing moisture damage that you know of, then that part you should take a look at. I had sheet vinyl in my kitchen, and was looking at replacing it with ether new SV, or LVT. I chose LVT, Since I had a nice flat floor, the LVT was to go right over the SV, with embossing leveler applied first. Unfortunately, because of the complete idiot that they sent to do my install, the company had to redo the job. (Yes, they lost money on this job.) They had to pull all the LVT up, and some of the old SV as well. (Which I wound up thinking was somewhat of a good thing, in my own mind, because I was able to see what good shape the sub floor was in.) The embossing leveler is even more important, I think, if you are getting a "smoother" type of sheet vinyl than what you had previously - most of the new stuff does not have the shine of the old, and the newer finishes will more easily show any uneven spots that the old SV. (SV really is a very forgiving floor covering - it's why it has been so popular for so many years, and also why so many people wind up disappointed in their "new" floor coverings that they replace it with.) There should be none of the old SV visible through the compound - make sure you ask them about their experience with this. It really is a skill to smooth out and level this stuff. The first guy that did mine did a piss-poor job on that as well, and at the time, I did not know any better. If for whatever reason, your SV is removed, then lay down a good underlayment like these... https://www.lowes.com/pd/SurePly-1-4-in-Whitewood-Plywood-Application-as-4-X-8/50124674 http://www.robertsconsolidated.com/products/accuply-premium-underlayment/ https://www.traxxcorp.com/products/matrixx-underlayment/ Read through this article for more info on underlayments for vinyl flooring. https://bct.eco.umass.edu/publications/articles/wood-underlayments-for-resilient-flooring/ Best of luck. I completely understand your choice of SV - it is hard to beat for wear value and "waterproofness".

100% I'd go with engineered hardwood over Vinyl plank. I just don't understand why some people seem to feel engineered hardwood is not a good choice. I think it is fantastic and is the best choice for certain installations. I don't think engineered flooring is in any way inferior. If you like wide plank you can get that in engineered as well - up to 8-10" wide. Although a more common size is 5-6" wide. We've had engineered hardwood down in our cottage for more than 3 years. We have had no issue at all with it and I haven't noticed any fading in sunlight and we have a lot of windows. Follow the manufacturers instructions and put in good underlayment - it really can make a big difference to the comfort and sound of the floors. There are so many colours and wood species available in engineered hardwood. I know you've said you spent a long time looking at your LVP - hopefully you can find some hardwood that is similar to what you were hoping for. I think this will turn out to be a lucky accident and in the long run I hope you will be very happy with whatever you choose.