It’s in the spec. Passive Poe. It will output what it gets in.
No negotiating with whatever is on the other end.
Best case nothing happens since ac3 will not negotiate (so I assume from a safety point of view no power gets delivered from the switch).
Yes. Should be perfectly fine, ports 2, 3 and 4.
Even 1, it will get no power (no negotiation, safety, no power) but if you power the device using other means, it’s a port like any other.
Not too sure about 5.