The point of Cavillrine is that Henry had been in the talks to potentially take over the Wolverine franchise but they decided not to do it. Gave us the chace to see how he would have been. Gambit is a cajun and Channing's accent was fine. Snipes and Reynolds have been ok for awhile now. Snipes came back because Ryan asked him to.
Gambit is Louisiana-French, better known as cajun. Although cajun is more Lafayette area than New Orleans area of Louisiana. Fun Fact: In the bayou region of Louisiana (south-southwest of N.O.) people there call themselves Coonass. Yep. Pronounced exactly how it's spelled. Lol
The same way Juggernauts helmet did. You don't use it yourself. Just like with Juggernauts helmet you put it on her to basically reduce Cassandra to a human rather than a mutant.