I've been running mine on Unraid for the last 4 years or so, and I have no complaints. Probably you can't go wrong with TrueNAS either. The big advantage of Unraid, as I understand it, is the ability to add arbitrary drive sizes in the future, if you want. But you might not run into that benefit for a while...
What is your sleep setting in BIOS? I had some problems with Linux sleep that got fixed by switching to Windows sleep. Maybe try that?
Onyx Boox eink tablet that runs android does all those things. I use Moon Reader on mine.
I did this before. The airport is a short ride from the center on the subway, so it's entirely possible to go to the center, wander around, and get back in time for your flight. It might be tough to find anything at 7am, though.