hi
1. that invisible issue happens every once in a while...especially when you create random mp or alt shot. what happens is, many plays come and go, so server doesn't have enough time to sync current players, so some players maybe invisible. best is to remake the game and everything should work.
2. it should not do so. if it does, then it's likely a flash issue on your end. I would recommend clearing cookies/temp files and trying another browser to see if it improves.
3. in regard to a spacebar issue, please see here.
-wgticon