I've been a sitter for decades.
While I've only been a caster for about 1 decade, I've been sitting during my job for many years prior. I've had bad knees since I was a teenager, so I always tried to figure a way to sit and work ever since.
Back to casting, I can't imagine casting standing up. I choose a chair to fit the Table/Workbench, then I mounted the bottom pour Pot high enough, so I could see the stream well. For a chair, I ended up with a vintage Samsonite folding chair, that is quite comfortable for me, for a folding chair...But 90 minutes is about the Max, and I have to take a break or quit casting.
I cast inside with minimal ventilation (window and small fan). I use only clean ingots inside and I do put a small amount of sawdust on top of a 1/2" of dross on a fresh pot of alloy, to create a isolation barrier, but don't flux beyond that.