While on Canadian PR
status you'll need a C1/D visa, which is a combination of two visas in one (C-1 and D). Once you are a Canadian citizen you are exempt from this visa. The airline should help arrange for you get this visa once you are hired. The visa requires an appointment & interview at the US embassy or consulate.
You will probably want a B1/B2 visa as well for personal or business travel other than as a crewmember -- I don't know what the rules are for your current citizenship (I'm assuming you're Australian?). If you ask/apply, the consular officer can issue you a C1/D and B1/B2 at the same time.