If this is part of their home there will be some expenses that are split with the rental as well. 

For many you are running full speed into a storm that you are not looking ahead at the clouds and unfortunately for those its not going to end well. 

I'd probably try adding on the bottom since there is more meat to the square profile there to connect to...but I'd trust your chosen professional. 

I am definitely looking at the DST option as well.

Depends on the neighborhood as well.

Also if they use house hacking they would have the other tenant that's paying rent would also be technically paying half of the mortgage as well.

With such strong credit, the interest rate should be well below the 8.00% quoted.

We were happy because we bought around 40 houses with only about 5% down out of our pocket in the end.They didn't cashflow very well for a few years because we had to get higher leverage to get all of their money back but rents are going up and they're doing better now plus we have a ton of equity that we can repurpose if we so choose.

If you think you can rent this out as a short term rental, then that is another story and I think you're 10k could be well spent to increase cash flow.

This seems like a costly fix, as well as a rental safety concern- The basement leaks, the basement is below ground and built into a hill, and there is always stagnant water in certain spots of the basement floor regardless of amount of rain, which only makes it worse.