The vaccinations here in Abu Dhabi are all for free, so don't worry about that. And no, they won't care if you don't have them all prior to joining.
I was told that the contract would be two years at my interview, and we got a bonus last year coz the airline did so good. They're also building accomadation like CRAZY so don't worry abt getting dismissed. Won't happen unless you do something UTTERLY stupid (like leaving the country twice when you're supposed to be working without even telling them, and mind you all i said TWICE).
Good Luck everyone =).