Using the upper versus lower bounds of these ranges seems to give me wildly different results in the calculator, leading me to many "potential maybes" -- so many that it seems like too much to ask for her opinion on.

Virtually no one wants to loose their home.  

I don't think I can push higher without risk of loosing him.Who can claim tax benefits on the property as the "owner"?

Since this is two separate buildings, you loose some efficiencies of scale.I usually figure 8-10% vacancy, but this is market specific.You should figure in management at 10%, even if you plan to self-manage at first.What about shared utilities?

It cannot be overly generalized too much or the cost looses its accuracy.     

You will see shopping carts and loose shopping bags that someone will have to deal with.

Contractors are going to give you a loose number based on not having any Drawings to bid from. 

Should an unauthorized occupant refuse to be bound by this lease, or refuse to leave on our demand, as the case may be, you agree to pay, as additional monthly rent, the sum of $25.00 for each day the unauthorized occupant remains on the Premises.It won't help you this time, but I always try to make each mistake only once.

I'd put an upper bound to the number of units, unless you really mean 16 unit to 1000+ units

This is tough because I would loose the current good rate I have the property.- Cash out refinance the 4 plex.