How feasible would it be to transition her to Section 8, and how long could this process take in Brooklyn, NY? 

I'm wondering about any potential regulations that might make this a more difficult process than I'm anticipating. 

depending on how backed up the county is it can e take a few months for court date. in essex county it took my mother in law about 8 months or so for the full process. she had an attorney, not sure if that sped anything up

But ya have to make some educated prognostications in life.Add this to the information your processing - What your talking about doing is eliminating around $4000 or interest expense (which is deductible anyway so really could be a real impact of eliminating $2800 or so) of debt in exchange for paying over $10K in capital gains tax (don't forget possible state gains tax as well).  

I'm in the process of vetting some seller financed deals for my solo401k portfolio.

What is the 20% processing fee?

I have a full time W2 that I'm passionate about, so I feel this process will allow me to time to make sound decisions as opposed to quick fix n flips.

I worked with an expert STR agent, Troy Nowak, who guided me through the purchase and negotiation process.

I’ve seen folks pivot their plans quickly if they discover one city has friendier permit processes than another.And yeah, the Phoenix area has some really down to earth investor meetups, from what I’ve heard, that can help you level up fast.What aspect of the business are you most excited to tackle first.. managing construction, or scouting out those under the radar leads?

Building a trusted team is key, so starting that process as you actively search for your market will put you in a strong position moving forward.