+1 on touching up all the seats, its the right thing to do, while your at it give them the valves as well, nothing like fresh seats and faces.
I don't know a powder coater who leaves the bushings in, I'm assuming these are plastic, they'll need a good clean swing arm for powder coating and to get the grease and other contaminants out, ya remove the bushings.
The rockershafts and cover can stay as they are, the picture posted earlier shows a pretty clean cover. Just wipe it down well and relube it before reassembling it to the head. The rocker shaft springs are fine,