Some of this I can answer, at least. 1) It makes your life easier and Home Depot (here, at least) seems to have them. For Zone 5, we're talking probably mid-August to Labor Day, but that can vary depending on where you are. Zone 5 is huge. 2) OK. You may discover patchiness from the color difference, though. 40K square feet is an awful lot to restart from scratch. 3) Probably, but if you seed the only thing you could use is Tupersan. Crabgrass is a spring germinating weed anyway and dies in frost. I'm not worrying about it on my restarting lawn. 4) Probably not, no. If you can spread the grass and see soil, you're home free. 5) Either aerate or slit seed, but not both. :-) 6) 40 pounds per 40 K square feet is definitely not enough, although any pH over 6.0 is OK. What was yours? 7) Compost or peat moss, about a quarter inch, definitely helps. You don't absolutely need to do it, though. 8) Yep! They sprout, develop, grow (fall being their prime season) and then nap off perfectly happily for winter. Some die off (some always do over the winter) but most make it just fine.

Please tell us what kind of turf seed you are planting. I assume you are using TTTF. This is the best choice since it will blend with your existing lawn, and can tolerate both full sun and moderate shade. It is also the best cool season grass for the transition zone where you live. KBG in Tennessee is possible, but it's an uphill struggle. Also if you do go with KBG there are some cultivars that do better in your area, and I can almost guarantee you won't find any of them in a big box store or bag put out by Scotts. Check the NTEP trials to see which ones perform best in your region if you want to go that route.

Glyphosate starts working immediately, but it takes about a week till the grass turns brown and looks dead. In most cases one application will kill all the grass and growing weeds. You can seed very soon after as glyphosate inactivates when it hits the soil, and it doesn't inhibit germination. The label on the bottle should tell you when you can seed after an application, but I believe it is 7 days. Slit seeders are good but only if they are working perfectly. Also blends of different grass varieties generally don't do as well as single grass variety blends in slit seeders because you set the seeding rate according to the type of seed you are using. It is hard to set a rate when you have three different seed types. Now for the bad news. I think you are too late to seed a lawn, especially one with KBG. The usual recommendation is to seed no later than 6-8 weeks before the first frost (a good frost, not a marginal one). KBG takes a long time to germinate and establish, especially when temperatures are low. Ideally you should have been seeding a month and a half ago. If you do seed what will probably happen is that the rye would come up, but since it is annual, it will die off. The KBG and the CRF will probably germinate, but then die off too as the temps will be too cold for the seedlings to mature enough to make it to spring. My advice to you since you already did a lawn kill would be to do a dormant seeding, i.e. lay the seed down in late fall or winter, preferably before a snowstorm. The seeds will lay dormant all winter and germinate in early spring when the conditions are right.

Slit seeding improves seed to soil contact and it improves the likelihood of soil moisture content around the seed resulting in better germination rates. Ideally, you'd want to bury seed deep to take advantage of soil moisture retention, but not so deep that the seed's stored energy capacity would be exhausted before the seedling's initial blade broke the surface. If the blade can't break the surface, the seedling can't produce it's own food through photosynthesis. Generally, bigger seeds have more reserves and coarser/sandy soil has less resistance to the emerging sprig, so seed can be planted deeper. You will find recommended depths vary anywhere from 1/8" to 3/4". Based on that, the depth of planting should be clear as mud. In addition to that crystal clarity, add the fact that no lawn is truly flat and the depth of cut that the slit seeder makes is going to vary. Here are some suggestions based on my experience: If the soil is dry or dry enough to collapse into the cut made by the slit seeder (creating a "U" shaped furrow), spread the seed first, then, go over the yard with the slit seeder. some seed will be deposited at the bottom of the cut and some will end up on or very near the surface, but most will be distributed in between where it gets the seed/soil/moisture benefit of slit seeding. Set the depth of the slit seeder blades so that it cuts no less than 1/4" deep in low spots and no more than 1/2" deep in high spots. Set the seeder depth before you do anything. Start high and make a test run (in a representative area of the yard) and lower the blade in increments to refine the depth. If the soil is just moist enough, that the slit seeder will make trenches (the type of cut that resembles the scoring that a circular saw set at 1/4" would make if run on a 2x4 piece of wood) and the trenches do not collapse when you walk on them, then run the the slit seeder first and then spread the seed and allow the seed to fall into the trenches. Roll the lawn if the roller will collapse the trenches and cover the seed. If not, top dress with 1/4" of peat moss. Set the cut so that the blades cut at no less than 1/8" in the low spots and about 1/4 to 3/8" in the high spots. FYI, I have had great success with KBG, but less than satisfying success with rye and fescue when I have spread the seed before using the slit seeder. Recently, however, a person on this site reported good success even with fescue. Hope all of that was understandable and useful.