I figure I can start out w/ maybe a 1/4" gap at the slider itself, do not install any molding until I see what maximum expansion on a hot day looks like.

It does get up to 80% ten days a year or so and depending on the way the unit is facing it could get hot.  

I really cant tell if that is membrane or asphalteither way I never really cared for flat roofsbest fix is to have it hot mopped with new membraneshould last upwards of 25-30 yearsor you could go with a metal roof, pretty easy to install and are good for life if installed correctly, flashing ect...enjoy

Apparently there was a 'hiccup' with the gas the other day, and my tenants needed to relight the stove, fireplace, and hot water heater.

Can she request a credit for days without hot water access?

I am doing BRRRR in my area, but now that Seattle market is becoming hot, looking to BRRRR out of state.

I supply curtain rods, but no curtains. 

The market in Indiana right now is hot.

Ask for a reserve study from the HOA to see the expected remaining life of some of the larger cap ex items, such as roof, parking lots, central heating/cooling systems, or hot water heater systems if applicable to that complex. 

Replacing south-facing windows with low-E windows will keep the units from getting very hot when the sun beats on them in summer.