Yes (do you mean Cheltenham gag?). And nylon cheeks make it more severe than the leather ones as they run freer, but the nylon ones are safer (leather ones can snap). However, a gag is only as severe as the hands on the end of the reins!
Yes a balding gag has loose rings, and can have a larger ring (mine is 10cm diameter, but friend has a bigger one!!!). They are called polo balding bits as generally used on polo ponies, but have one for xc!!!!