MTRs fall into the standard long term rental( 30 day +) category and will follow those regulations set for Long term rentals.

REI is a long-term venture; if you cannot hold this will be a very difficult process.  

Owning a duplex at 20 is a huge accomplishment, and it’s inspiring to see you’re already planning your next move.From my perspective, real estate investing is a long-term game focused on building equity, paying down debt, and maintaining stability over chasing short-term cash flow.

Depending on your current rate or if the current loan is short term or long term.

As long as the property cash flows, that's what is mainly needed. 

For a long term investor:Would it make sense if you could buy the home at a steep discount and then let the owner stay rent free for a specific period of time?

Honestly with an interest rate like that you could even not pay off your primary and put any excess capital in a high yields savings account and be financially further in the long term.  

I have Mutuals and Indexes- I have always played it safe, however, I've waited way too long to invest in Real Estate.

And then you could take your time shopping for long term financing once you own the property.

I have a variety of contacts and I'm pretty sure I can get in touch with destressed property owners long before auction day (years before auction day actually).