With regard to my parents, I want a good relationship with them so they can build my credit history.

There is a processing fee if you choose the credit card option, but a direct ACH has no additional charges.

Also, credit score minimums are higher- often requiring a middle mortgage FICO score of 720 and above.

What documents do they require, what credit scores do they allow, how do they verify previous rental history, etc.?

They offered to give me a credit on a future loan.

Local credit union.

Financing through a personal loan usually offers better rates and lower costs, but using an LLC builds business credit for future investments.

I had belatedly realized that FHA goes off personal credit and therefore I couldn't use the LLC for it.

You are right, when the inspector mentioned the possibility or prior water damage is when you should of had that basement inspected by a contractor/professional and not listen to your agent.Gregg is right, the sellers were aware of some of the damage which is why they gave you a 5K credit. 

Hi Scott, you don't need to be a first time homebuyer to use an FHA loan and you don't need to be low credit (as many would suppose), but the product probably appeals most to low-credit first time buyers.