As a Dallas REALTOR, I am pretty comfortable with the pulse of this market, but you are right, there are a number of changes happening. 

I plan to grow a real estate portfolio in the future to the point where I can support myself comfortably throughout my entire life and leave my day job. 

(or the debt that give you a poor credit score rating). " What are we going to do with the free'd up income" and finally " How much money will i need to retire comfortably and when can i retire?"

For anyone in my shoes would you take it to small claims or collection agency?

In any event, it all seems good enough that I’d feel comfortable moving forward once you get positive landlord references. 

Any advice for someone in my shoes?

I'm im your shoes and buy turnkey properties that don't need much work.

I wanted your opinion if you would feel comfortable  renting 2 rooms to 2 individuals during the Covid-19 pandemic ?  

However if I were in the other people's shoes I don't see wanting to give you a no-payments loan for $200k for a year and a half, and only making 4% on that money for 5 years unless all the co heirs are independently wealthy (possible but seems unlikely).  

I would counsel them to do a 5 or 7 year with a balloon at the end (which could be negotiated if both parties agree again into another 5 years of installments), but, anyways.In your shoes, I'd try to negotiate it so you get help and advice and the partner is along for the ride, but give up as little long term free cash flow and - more importantly - equity in the property as possible.