Do not EVER use the security deposit for repairs or rent while the tenant lives in the rental.

As title states am interested in purchasing a 4-plex, owner occupying one unit and renting the 3 other.

If you are renting an apartment, look at apartment comps.

My questions here would be around the anticipated appreciation and any potential for improvements - either forcing appreciation or increasing rents.

Not the same as “Rent to Retirement” - which was initially confusing to me. 

I almost made the mistake of paying a Philly guru who was going to teach me the ins and outs of buying section 8 homes and after reaching out to others on BP who invest in better market real estate, realized its incredibly risky.I have 12-doors in Detroit, 3 of which are rented to S8 tenants and have been for nearly 5 years now.The experience has been pretty solid for me.

@Neil Warren There can be great turn-key deals you have to know your rents and know the comps in the area. 

Property Manager says I can get at least $1900 a month in rent on the open market and $1770 going Section 8 route.

So knowing the rent levels and operating expenses, to get to NOI.  

My guess is yes in which case, get a copy of the document and let the family pay the back rent.