Slides and auto levelers dead
Q1: you use battery power to start it, but not while running it; while running it charges the batteries. But even while running, everything that uses DC power still runs off the batteries.
Q2: yes (except AC and microwave, maybe TV, anything that runs on A/C power directly)
Suggest you fully charge up the batteries which may take a few hours on the generator or 2-3 days on AC power using the converter. Even though one slider worked OK, they draw a lot of amps and then there wasn't enough juice left in the batteries for the others. If they don't work on a full charge, that's a different problem, perhaps fuses which you can check in the meantime.
2016 FR Forester 2401R
Towing 2014 Honda CR-V