While the Romans certainly encountered warrior women when fighting against the various Barbarian tribes, women were not allowed to serve in the army in any official capacity. Women certainly did follow the army as part of the horde of camp followers however that decreased after the reforms of Marius. As to whether a woman disguised herself as man to serve there's no evidence of that yet either. It's highly unlikely that a Roman woman even one of any class would entertain the idea of being a solider either.
As to female gladiators yes there were female gladiators called gladiatrices however they were uncommon and little is known about them specifically.