Ana
Congratulations - see you out on the line sometime. Sorry that I couldn't give you interview advice in advance of your interview: My interview was so many years ago (20+) that I don't think the experience is relevant in any way to what you get given.
Things were more primitive then - If you could eat and stand up at the same time, you were in!
Sometimes I wonder how I got through the process - and sometimes, I think Britannia wonders the same thing.
Your flying patterns will be determined by your base, and aircraft types on which you are checked. I need to know your base at least to answer. Basic accommodation when flying is paid for by the company, but the package is complicated and will be discussed in your contract, as will the salary details (an open forum is not always the best place to be specific about salary packages).
Britannia is an excellent company to work for in many ways. They tend to be good at the big issues - they can also drive you into a blind rage with the small ones at the same time. Flying is still the best job I know of, and since "they" own the aircraft, "we" tolerate their less attractive activities.
Good Luck