Questions

I'm not familiar with Indiana, or don't know (You didn't mention) what kind of grass. But, a few rules apply all over.

1. NEVER use a weed & feed product. The weed part is a herbicide pre-emergent. If one uses a pre-emergent, it needs to be applied before weeds emerge. I suggest to not use a pre-emergent, unless something like corn gluten. In addition, the herbicide can damage or even kill shrubs & bushes.
2. Grass does not need fertilizer until 4 to 6 weeks after spring. Therefore, the weed and seed is generally too late to help with the weeds, and too early to fertilize. A rule of thumb on time to fertilize is after the the third required mowing.
3. As to poor soil, clay; there is probably nothing better to revitalize soil than compost. Spread about a half inch thick layer of compost over the yard this spring, and again six months later. Do this for two or three years in a row, and your soil will be GREATLY improved. You can either make the compost yourself if you have enough raw material, or purchase it in bulk.

About the best I can tell you from the information you provided. You might consider discussing with your county agent, or at least a good nursery.

Good luck, Bob-tx

Thanks for the reply. I hadn't even thought about the county agent, so this was VERY useful if with the scant infor I gave.