1. I think the list of stuff will all work together. 2. Since you're getting a bronze faucet, does ICE make a bronze extended flange? Or Rohl? 3. The flange that comes with the GD will be a standard flange in stainless (most likely) and not usable. It won't fit the sink. The stopper will be reusable but also in stainless or just plain black. 4. since the diameters of the flange/stopper are standard, you can buy different ones from ICE. 5. A stopper for a continuous feed is so you can keep water in the sink. It's basically a round disk with a grab knob on the shiny side. A stopper for a Batch feed also has the T-shaped bit on the bottom that activates the GD when the stopper is inserted in the correct position. I'm going to guess that a '2-position' stopper is for a batch feed model.

Your problem is quite common and not nearly as difficult to fix as you might imagine. The flange and cup shaped metal part with the cross at the bottom that you are looking at is properly called the "Tub Basket". On the end of the drain line immediately under the tub hole there is a casting called the "Tub Shoe" that has female threads. Once the Tub shoe is properly aligned with the tub hole from the bottom we apply plumbers putty to the underside of the flange on the tub basket and insert the basket through the tub hole from the top and screw it into the tub shoe. As the basket is tightened down from the top it in turn pulls the tub shoe upwards to insure a tight seal. (There is also a rubber gasket between the top of the tub shoe and the underside of the tub). Such is common to all things, in time the plumbers putty will dry out and crack resulting in a leak. To repair the leak you will need a "Tub Basket Wrench" to unscrew the tub basket. Once you have the basket out you can clean the underside and apply new plumbers putty, which is the industry norm, or you may elect to apply a generous layer of cf clear silicone sealer (Plumbers Goop) then insert the tub basket back into the hole and use your basket wrench to tighten it in place. As you tighten the basket in place the excess plumbers putty or silicone will squeeze out around the flange. That is to be expected and it is a simple matter of wiping the excess away when the basket is tightly in place. A word of caution here. If you use plumbers putty the drain can be used immediately but if you elect to use silicone you must allow 24 hours for the silicone to completely set.(personally I prefer the plumbers putty because once a basket is set in with silicone it is nearly impossible to ever remove again, and contrary to public opinion, silicone will leak in time due to the minor flexing of the tub in normal use.) Some handymen will tell you that you can remove the basket by inserting the points of needle nose pliers through the cross and turning the cross that way. Don't you believe it. When trying to remove a basket in that manner there is an extremely high risk that you will break the cross out then you will have a real chore trying to remove the basket. There are dozens of varieties of tub basket wrenches ranging in price from about $7 for the simple cast iron type to well over $60 for the professional grade type. Fortunately even the el cheapo cast iron type will do fine for the limited use that a homeowner might need. You can find a basket wrench in any local hardware or home supply store. (If you would like an illustration send me an email requesting it, and i will be glad to return it to you)

A window can be installed 100% water tight with or without a flange when done properly, I would not worry about that (or maybe you should if your contractor does not know how to do it). The one thing that I would say though, is that if the exisiting unit is a full frame unit, the insurance should pay for the same. I'd only accept a replacement/insert as sufficient coverage if that is what you already have.

I have a stainless Kohler sink so can't comment re: your sink color, but I do have the Simplice faucet in vibrant stainless and the Kohler sink flange, which is very nice. I also ordered a drain strainer basket (that little piece that you put over the drain so water can drain but bits of food get caught in the basket) from Kohler. It's fine, but someone recently posted a much nicer one from a different mfr. It was standard size, though, so should fit your drain. It was maybe 2 inches deep, shaped kind of like a bowl with vertical sides, so it would hold much more stuff. I'm sorry I can't remember who posted it. It was too late for me.