Aside from back taxes, water bills, liens, etc foundation problems could be an issue, which tends to be the biggest pain.

But some things to consider when you're scanning properties:  Single story, slab foundation, 3br/2 full bath at the least, wide halls/doorways for wheelchair access.  

Any suggestions to build it further or to build a better foundation for a loan?

Schwab, T Rowe Price, etc) is probably not set up with the knowledge and experience to do this.2) What you want is what's called a "Self-directed IRA" (SDIRA). 

Check for foundation cracks and standing water around the outside of the house.Other than that just look at anything that might keep you from getting the max amount of rent for that area.

Home was built in 1900 but sat on a block foundation.

That’s a solid foundation, and you’ll figure out the rest.

If you do everything properly in running your LLC, such as keeping separate business and personal bank accounts, not co-mingling funds, not dipping your hands into the business account to buy person items, tracking meeting minutes and resolutions, etc. then theoretically if you are found at fault the judgment would be limited to only assets owned by the LLC. 

After I had an inspection done and found there were foundation issues, the seller agreed to negotiate down a bit more to compensate the costs of foundation repairs.

I happen to know the property as I drive by often and am aware it needs some foundation work, which can cost up to $10,000.