I told my dad I wanted to buy his house and he was absolutely on board for that. 

2) When using other people's money to invest, what is the best way to set up an agreement on a limited budget?

Typically in my experience at a large real estate development firm, we worked with local attorneys on the appeal process every year.

Have been reading up on this a bit and it seems if I get it into a roth ira it can be used for downpayment funds eventually with lower taxes removed?

If you are wanting to sell your real estate property, but are worried about paying taxes on the capital gains, a great strategy to consider is a 721 Exchange.

Have begun talking to lenders but am having trouble getting good quotes on interest rates.

Will having that home on our credit negate us from being able to seek additional loans for other properties? 

Today I looked on another site pennymac to see the value it said and there was no information for the address of my property but when I added #2 to the address and it was able to come up with an estimate for my property.Do I need to be concerned that these apps are showing my property with the wrong address?

Down payment, credit score, and pre-payment penalty (on DSCR loans)  effect the interest rate and the cost of the loan a great deal.

underwrite the loans properlyIt's great to hear that you're focused on properly underwriting the loans.