I wouldn't want any competition for water and nutrients. Pushing top growth isn't what you need to focus on, it's the root situation. Instead of planting more, I'd haul in several truckloads of topsoil and a tractor service and just get it over with. the alternative is years of top dressing and reseeding and having poor quality appearance.I would add 4-6" or more inches of topsoil, the more the merrier. As much as you can feasibly add.

When should i Round up the lawn? It all depends on when you are going to drop seed, and if you are going to fallow for a bit. In actuality you can round up a few hours before you lay seed, but that isn't too practical for home lawns. For a home lawn, 2 weeks is probably the least amount of time I would suggest, since after about a week you should know if you missed any areas, and you can reapply. Also when applying it, it is important that everything is green and growing. Dormant, or sluggish grass/weeds won't absorb it, and they can wake up during the renovation. So most people recommend watering a few times a week before you apply round-up, and afterwards as well. Which type of RU? I saw blue and green cap ones. Just use the straight round up or any brand that has glyphosate as the main ingredient (I use Ortho's from Home Depot, it's a little cheaper). The other kind has another chemical that makes things turn brown in a few days, but I don't see the need for it when renovating, plus it costs more. Should i drop the Calcium lime before i drop seed or after? Drop Potassium sulfate before or after? Your next liming should be 90 days after the one you did this spring. If that coincides with seeding then I would wait till your grass has been mowed a few times. When seeding I would use a half app of starter fertilizer at the time of seeding, and the other half after it has been mowed once or twice. So then lime 2 weeks after that starter app. The starter is high in K, so that will count towards a K app. Would it be smart to fallow the lawn? It's not a bad idea, especially if your weed pressure is/was high and you don't mind having a brown lawn for a month or so. Better to do a TTFF/KBG lawn or just KBG? It all depends on you and your lawn. If you have a good amount of shade, TTTF is going to do better. KBG makes the best lawn in my opinion, but it has a longer establishment and maturity time, so don't expect a full KBG lawn to be really nice next spring. It really hits it stride in its third year. TTTF/KBG is a nice compromise, but there can be some issues with color matching and growth rates. For the TTTF cultivars, those are all good. I would definitely use Bullseye, it is one of the best. LS 1200 is good, but it does poorly in shade. For the KBG: Bedazzeled: A good choice, not too dark, good spring green up, not sure about it's disease tolerance. Prosperity: A very dark cultivar, might not blend well with TTTF due to color, but I can't say for sure. It also has some disease issues, might not be the best if you are just using one in a mix. Moonlight 2: Not sure about this one, check the NTEP's and it's tech sheet. Emblem: Not a good choice. Seed on the market is old as it's being discontinued. A very aggressive cultivar, might dominate lawn. Also very dark. Has a very long dormancy period as well, i.e. slow spring green up. Blueburry: One of the darkest cultivars you can get. Might not blend well, and it might have disease issues. Moonlight SLT: A good cultivar, supposed to have some shade tolerance. Check the NTEP and tech sheet for mixability. Award: A compact midnight, so it's going to be dark, and might not blend well. Does OK in shadier sights, but not great. There are a few others to look at. Bewitched: A dark cultivar so be warned, but does well in shadier areas, not too aggressive, and has good disease tolerances. Unique and Apollo. Not as dark as some, good shade tolerances. America: An old standard, has been around for a long time, but still performs well. Has some shade tolerance, not as dark as others. Orfeo: A very fast one to germinate and establish. Blends well with TTTF, but is aggressive, so it can take over. In reality, color might not be as big an issue as I make it out to be as KBG really needs good soil high in iron to reach it's full potential while TTTF seems to be less finicky to iron levels. Many of the growers say a lot of their cultivars blend well with TTTF. If you are really worried about it though, then just go with all TTTF or KBG.

With hostas, nuking them from orbit is the only way to be sure. And even then, I wouldn't put money on it. You can try damping a cloth with Round Up and rubbing it on the leaves, dampening them all with the Round Up. That should take it out. This looks like a really young lawn, so it's too early to make an assumption as to how it's going to turn out (hint: I think it actually looks good for its assumed age of less than 2 months of decent growing weather). We're getting close to feeding time, but with a young lawn, I'd be gentle. Perhaps something like Milorganite would be your best choice as it won't kick the grass. A synthetic would be a bit of a stress on it. Milo can go now, synthetics should wait until the end of May. I think you're going to have a fairly nice lawn, but don't forget to water through the first summer--probably more than you'd want to, but it's only for this year. Any remaining holes can be overseeded in mid-August when night-time temperatures just begin to drop off their heights. Your assumption there is correct!

Apparently you didn't read anything from this forum about seeding. Well, maybe you read others' opinions, but in my opinion, you have spent too much money to get to this point. I'm going to sound very negative at first. That is not to make you feel bad, but more to deter others following on what you don't need to do. The bobcat is a nice tool for carrying stuff around, but it is not great for leveling the soil. I watched a video of a guy doing that last night - it was hilarious - like watching Laurel and Hardy trying to push a piano up the steps. The proper tool for a do-over like you did is a tractor with a box blade. That tool could have done in one pass what a bobcat might take all day to do. If you are paying by the hour, it makes a difference. New topsoil is not a solution to old topsoil. Your new topsoil used to be someone elses old topsoil. You're simply trading your old issues for different issue. Old topsoil can almost always be restored to a very healthy condition with organic fertilizer. The recommendation to aerate first, which I disagree with anyway, is so that you can drop seed down into the holes where it is supposed to sprout better. I don't get that, so at least you have not wasted your money on aerating. Looking at the current situation, spread more seed to the thin areas, walk on it to ensure the seed is making good contact with the soil, and continue watering. When the new grass is 5 inches high, mow it back to 4 inches. You don't need more soil and don't need any hay. In fact hay is a serious problem for new grass. The product you were looking for was straw, not hay. Hay has weed seeds while straw does not. All the water you need is about 5 to 10 minutes, two or three times a day. If your soil ever gets soggy, that's way too much water.