Suck out as much as possible, do it after the first day after adding, it will be loose. Yes turkey baste helps! Get EVERYTHING last bit of it you can.
GFO should be fine.
ZEOvit unaffected, leave it running (I run Zeovit and have used chemiclean a couple times last year)
Best bet for aeration is to take the top off your skimmer and let it overflow. I would recommend leaving your vortech's as normal so your fish are least stressed.
Skimmer will be skimming very wet after for several days. It will pass
make sure carbon is out during and you put fresh carbon after.