I came to this forum thinking I knew something about lawn care, too. I already had 6 lawns under my belt and had taken a couple courses in college. Turns out everything I thought I knew was wrong. To bring that home to you, here are some ideas.

You don't need to spread lime unless and until you have a good soil test that tells you that. You probably have a county extension service that will test your soil for $10 or so, but I would strongly suggest you go to Logan Labs in Ohio for their $20 test. They test for more stuff than the extension service and their results are more reliable. A good test will distinguish between the two types of lime and give you an idea how much to use and when.

YOU NEED DENSE TURF NOW TO FIGHT OFF WEEDS IN THE SPRING. Was I shouting? SPREAD THE SEEDS NOW. Oops! There I go again. You have exactly the right idea on this. Don't let anyone talk you out of it. It is possible to get too much seed on the soil but that doesn't seem to be a problem we see. If you have full sun in the back I would encourage blending 10% Kentucky bluegrass into the turf. It will become brown in the winter and possibly in the summer if you forget to water. But it has the ability to spread and fill in the thin spots in the fescue. If you have shade in the back, they use fine fescue in the seed mix. It will remain green all year.

Then there are two huge things I didn't realize about lawns. First and most important is to water deeply and infrequently. Deep means 1 inch all at one time. Infrequent means monthly in the cool months and changing gradually up to once per week in the hottest heat of summer. This makes all the difference to most people. Weeds seem to disappear and the grass dominates everything. The other thing I learned here was that organic fertilizer really works. In class it was sort of just dispensed with as being hocum. Well, back in the 1970s nobody knew why it worked. Now that we know, we can use it correctly and use enough to get the job done. We can also not use the organic stuff, like manure, that doesn't work.

Your St Aug should be mowed at the mower's highest setting all the time. And I think your back yard should also be mowed at the highest setting, but that's more controversial. Somewhere between the middle and highest is fine.

Awesome. Thanks for the help. Ya I mow at the highest setting my mower goes. Back the front and mulch the back. New blade to get a good cut.

Last question, ha, I promise. Do you suggest doing it all at once? Spreading new seed and fertilizing. I don't know if the fertilizer is to harsh on the seeds.