Live in one unit and rent the others, this would give you additional units without extra mortgages, and help scale your business quicker. 

At this point, we're just looking for a little extra income and the possibility of doing this into retirement. 

You wont be wasting your hard earned money.

That extra $500 isn't saving you money...it's costing you money you aren't spending now. 

There may be a few extra forms to fill out and documents to provide.

As well as the unit i'll be living in to use FHA loan, but I think I'll airbnb my unit out to bring some extra income.  

I'm not really excited about leaving an electric heater running unattended, nor do I think that curious, uneducated minds would think it was necessary to run one in an unoccupied space, nor would they appreciate the extra heat in summer, or the extra expense added to their electric bill.I'm wondering if anyone has tried any of these, or if they have success doing something else to help cure a damp basement.Thanks in advance.

If you're looking to get into flips, being your on Realtor will save you the 3% commission when you list the home, and if you are buying off of the MLS, you can earn a 3% commission for purchasing the property. 

I've been told by my bookkeeper that I should 1099 him as a subcontractor to avoid extra taxes and also because partnerships, "tend to never work out."

Without a lease, there are extra hurdles to evict.