Easiest may be to loan her the $80k in exchange for a first mortgage and a will stating you will inherit all or portion. 

Do I give up some cashflow when I buy a larger apartment building in exchange for economies of scale?

Volunteer to work for them or with them in exchange for their knowledge.

Escrowed funds from an end buyer can't be used until consideration has been exchanged to pass good title in the first transaction before the second transaction.  

Precisely, it will not hurt you to accept this request, yet it might help you in the future. 

Hold onto the property for a few years, then swap it out with a 1031 exchange for a "better" property.

I have access to mls when I need to crunch more precise data, but I use the Zillow app on my I pad when I am looking at houses, to get me a quick synopsis of what a neighborhood looks like, and to get me close.If you use the "yellow houses" those are solds they are reliable comps to use to determine arv.

Could you pass the deal to some one else in exchange for a modest "bird dog" fee?

I had offered to pay a few bills in exchange for a few of the units through quit claim deed currently owned under the association name.

I'd exchange rental #1 and rental #2 and buy a small apartment complex.