To make it simple…the investor is trying to buy your property Sub2 and needs you to refinance it into a long-term loan First.The investor does not have to ask the bank’s permission.

I recommend a simple spreadsheet to check your math and it will make it simple to adjust each year.End the complaints.

I guess my simple answer is several questions back to you.  

That said - I think a simple muitual fund would give me better returns on the same money ($900k) at 8-12% (i.e., $72k - $108k). 

This is as simple as going through neighborhoods and finding distressed properties, and learning how to make them offers.

They’ll have a deep understanding of the market and a strong network, which can help you identify the best opportunities.Owning rental property isn’t as simple as it might seem.

You defiantly want legal protection as stated by @Max Wilhite@Jonathan Bock is correct about keeping it simple. 

Those are simple financial questions.

Then it's simple, build the home, find crews to do the work (you should already have them basically from the prior step), excavation, concrete, sealing, framing, roof/gutters/siding, windows, insulation drywall, plumbing, HVAC, electrical, finishes, etc. basically in that order.

You can usually find some events by doing a simple google search.