Get the environmental study done 3.

(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.

Oh, and also what’s the impact of this higher mortgage payment each month if you don’t do this?

One book that isn't real estate related but has had a huge impact on my life is "The Slight Edge" by Jeff Olsen.