I'd like to use this to make an "all-cash" offer on a SFR, and then convert that to a conventional mortgage to pay off the HELOC.  

My question is, does anyone know if it is possible that I can convert the building into a 4 units apartment with that Mixed Use zoning or do I have to request a change of zoning?

I don't know your area, so I can only write to my experiences in PA.You don't really convert your property to Section 8 (S8), but rather sign a lease with a tenant who happens to be funded by S8.

We are planning to purchase a home and convert it into a community living space for people in recovery.

My idea to achieve this is to convert the studio into a short-term rental.I’m trying to determine if I’m forcing this deal to work by relying on the short-term rental strategy or if it’s a reasonable approach given the numbers.

Rufo, so you are violating the HOA rules so I don't think they would cover anything if it is the fault of your guests.This will eventually catch up with you and could result in some big fines so maybe think of selling this or converting to a LTR instead.

.- The commitment letter says if I convert the leads given by the TL I would get a 50-50 split and if it was my lead through my COI/SOI while I was on the team, then it is a 80-20 split. - I had a few COI/SOI leads while being on this team who have not signed any papers with me or any one on the team as of yet and won't for the next 2-3 months.

But that's still a far cry from converting an R1 to R2 .

You can always sale on your date and convert appreciation to monthly cashflow.  

I plan on converting the barn into another sleeping space and indoor/outdoor rec room.