Will that increase my chances of being able to refi in spite of my DTI ratio?

Chances are it is holding you back dealing with the stress of passing.

Your $200k rehab likely will cost higher than your estimate - unless you really have a lot of experience in this;  Housing market has higher chance to lose 10% value vs. gain of 10% in the next 12 months due to the recession;  not sure if your profit included brokerage cost or other holding cost.For units next to beach, I assume you plan to do STR. 

Then wonder why no one emails them back or picks up their phone calls anymore. 99% of email blasts are overpriced junk, you're not going to get many chances with buyers before they start ignoring you if you do this.

The thing is, i was born outside USA and i never been there, so i dont have any score or tax history and many lenders told me that no normal bank would accept me even if it is for an investment MFH so i spoke with several professionals.Most of them told me to pay taxes as a 1099 two years back and start building a score somehow with credit cards and so on, because no lenders or banks cares about taxes of expats cause they dont consider them "real" if they are under the 100K annual cap, that most people lie about that kind of info, sounds really stupid to me but i dont know really.Realtors told me i should buy a first house with some bad credit, near 10% interest, 40% Downpayment for 15 years (something not really nice) and with that i could start to build a record and obtain after a few months a conventional 4% interest, 25% Downpayment and 30 years (normal mortgage) I would like if anyone could give me any kind of advice on this situation, i just want to start RE portfolio in the states and i think that with the chance to have good credit, its a joke to go full cash when buying !

They get a chance to know you and you get a chance to get your finances and documents in order.

If rent is not paid, I would just start the eviction process.when you serve notice, is very good chance they will either move out or they will contact you and try to negotiate something.

I don't know you or your wife, but I would bet heavy on the chance she would enjoy EVERYTHING you do with RE after something like that happens!

Now of course you would want to model out the various scenarios and identify a price you can pay that makes sense, however non of those scenarios will have a chance to play out if, for example, you bought a note that has sold at a tax sale and redemption period ends before you claim and redeem the taxes.  

Once they meet and start talking, there's a really good chance someone will start making agreements behind my back and things go south.