You can of course try to file an eviction on him, but chances are if he's really leaving you'll get nowhere, especially with Covid, so try to negotiate as best as you can and make sure you cover this on your next lease. 

I'm trying to see if any of my calculations are off.2 - There is a chance I may be moving back to the USA and knowing this information may be a good first step to know what to do once i get there.

There is no issue with this on its face, but if you ever need to replace the management company, and the in-house manager was charging below market rates (there is a chance they do this to make more money on the sale, since they are the flipper too), your returns will take a hit.

5) What are the chances of getting permission to do it?

And someone jumping into this as a complete newbie can expect that they have a decent chance of making some expensive newbie mistakes.

offer her cash for keys. 1/2 to 1 month of rent, and chances are she will leave if she has a conscience because she knows obviously that she has been ripping you off. 

For eg. for a 2b2b in San Diego, rent is 2200$, after 2 years, it could be come 2400$, but my mortgage is 2600$ or above.Is there a chance in the future, I could refinance it with more equity built up, thus lowering my monthly mortgage which could then be easily covered by tenants? 

Either your thoughts on the market value are off, they are hurting for money (therefore check the quality closely of these units in process), or there's little chance of getting these at $200k lower than market value unless these folks are smoking something.Last thought:  you'll want to talk to an insurance broker who does commercial policies in my opinion. 

I don't totally understand the idea of "equitable title," and what are the disadvantages of not holding the deed, etc. 

AND, it will give you the real chance of enjoying the greatest city in the world.Good luck and reach out if your in Poughkeepsie!