The idea is going to be to use his money as a portion (or all) of the down payment. . .so I'm really trying to ascertain what to do in the way of interest rate, frequency of payout, etc.

After Foreclosure, how can the new owner of the property ascertain if it has indeed been vacated by the tenant or in other words can be legally possessed by the new owner?

I know of some fly by night REI investors that still got screwed royally by the courts as they did not have there ducks lined up and the suing party was able to get past the legal vail to ascertain damage rewards which the defendants homeowners insurance did not pay because of changes to deeds and land/property use (no longer a primary property but used as income property) without notifying the Insurance company and mortgage lender. 

When you close there is advanced property tax, title you need to ascertain that  $2K is adequate to cover it. 

Adding on a huge thank you to @JoshNix for kindly talking me through some beginner distinctions and helping me ascertain my goals. 

It's as certain as you can expect.Real estate, on the other hand, brings with it uncertainty.

Fair point, but is this something that can be ascertained with due diligence?

Ascertaining the cause of the excess moisture (relative to the outdoor humidity and temperature) may help with the condensation that's leading to the mold.

I would suggest that you interview several Realtors and ask them the following questions, to ascertain if they are truly Investor Friendly, or if they are throwing you a sales pitch.

If principal, is it limited to an ascertainable standard or is it discretionary?