EDUCATE YOURSELF - yes, it will take time, but will lead to a selection that better meets your expectations & avoids potentially costly surprises!

You might also meet someone that could be a potential business partner.

For example, in a rent to own, the tenant/buyers are responsible for repairs and maintenance.

Sure it may not grow as fast as the potential appreciation of a property in Hawaii but it will reduce risk.3.

  - Lastly, does anyone have any spreadsheets, calculators, or other tools for quickly assessing the feasibility of potential investments?

You would qualify based on the potential rent of the property. 

But if your friend is not the actual buyer and signed the mortgage docs this could be impossible.sell in 2 weeks for cash. this can happen. as stated a above payoff the loan in cash now.If your friend is in title to the property they can file BK  which can be pretty devastating to someone long term but gives them time ..

I asked questions of the win-win buyer and after a little back and forth, it seemed like the buyer is just overpaying for the property to get owner financing. 

I was excited because the basement needed an egress window and I was viewing it as a potential additional room and house hack and future rental possibility. 

As well of assessment of demand in the market for these potential cabins Thank you!