All sounds great, he sounds quite happy in there
I also wouldn't use a hamster ball, to be honest the regular balls are too small for Syrians anyway. Running around supervised in an escape proof room can be ok for tame Syrians, just make sure they can't squeeze under anything at all as they can be very crafty especially if they don't want to be caught. It might be easier to make a playpen with tall sides, definitely while he isn't tame yet. You can make it as big as you want, just make it out of cardboard or some people use correx. Very few playpens are actually Syrian proof so can't be of much help there I'm afraid.