No player tanks result from a player quitting a game. Instead of the tank being removed, one sees the nametag vanish. The turn of the tank is given to other players on the team, rotating between them if needed. This does not occur when all members of a team quit, as the game automatically ends at that point.
Weapons available are random, based on a default set of weaponry. The player controlling the tank cannot use custom choices - the only weapon that can be used is predetermined. They cannot use item drops.