I'd have to go back an reread to be sure, but iirc the "moving the benches" thing is rebel-AS specific and is because of them holding the Hall in a tent. Especially while on the move from Salidar to TV. "Oh hey, we're on the move. Ok now we're going to stop for the day, let's have a Hall meeting. Workers! Unpack the Hall benches and move them into the tent! Which we also need you to set up!" Even on days when the army doesn't move, they probably move the benches off to the side when the Hall is not in session and use the tent for other things.

As far as colors go, I dunno. I always thought of the Amyrlin's seat/throne as being made of solid gold, or something equally extravagant and ridiculous. And the Hall's seats being maybe marble or something similar. And only the floor tiles being the 7 colors of the ajahs. I freely admit though that I pretty much ignored RJ's descriptions and imagined it how I wanted.