You'll save on legal fees setting up the LLCs, annual reports for the LLC, insurance discounts possibly, having 2 umbrella policies - one for personal and one for parent LLC, and the biggest impact could be on financing options that change when a property is in an LLC - it then becomes commercial loans at a higher rate etc.   

It needs new electric, roof, and impact windows and doors.

If he finances the loan, he gets a monthly paycheck that he can spend and he's only taxed on the amount he receives.if he wants a big chunk now for a vacation or to buy a sports car or just to feel good, figure out how much he needs and try to negotiate a large down-payment and then finance the remainder.Recommend a couple options and then ask him to talk to his CPA and see how each option would impact him, how much he would save, and how much he would earn.

(If current value is $120k, then make sure your Dad talks to a tax professional about potential impact - there might be no impact, but it depends on his situation)How long do you expect repairs to take - days, weeks, months?

All too often, we see incorrect rent rolls, shoddy bookkeeping, and a variety of other factors impacting CAP rates and the reported NOI. 

I think you need to provide more information...total cost to close the loan impacts your ROI, not just the interest rate.

Understanding how the markets work, supply and demand, trends, government impact on markets, and being able to predict patterns will help you a ton.

Each decision in the process impacts your business down the road, so it is really encouraged that you have someone assist you with this process. 

Will the weather in the region impact this by need funds for snow removal or flood insurance? 

We're concerned w/ the impact that will have on the value of our house.