This "master plan" is basically starting and developing a portfolio of rental units. 

The three family has not had a recent appraisal but seems to have conservatively about 50K in equity in my market.This is just the basics of my situation.

My friend (who lives in the area now) and I are considering buying a very basic, 1 or 2br1bath condo that we hope to maximize rental income through 30+  days medium-term rentals- since I lived there and even my last visit earlier this year, I actually didn't realize how stringent the str regulations had become, and I still don't know how small-time landlords actually deal with the laws now.

Talk to a CPA.Yes there are depreciation implications, as you would basically be stepping into the shoes of the previous owner of the LLC.

He basically said it was way more hassle than it was worth because of the extra filings because it makes me an scorp now.

You can even find some basic wills online for pretty inexpensive. 

I understand the general idea of the SDIRA and even the basic regulations Carl has discussed above.

So, after way too much preamble, my question: Is it worth doing a BRRRR deal where, you put down 100% cash (by pulling it out of other properties, assuming I can figure that out) on a house for about $950k, renovate for $250k or so, refinance on a property now worth $1.4M but then basically just are cash flow neutral after?

It basically zeros out the largest expense any household has: housing.

Now I've seen many contracts which look very basic.