a) Learn German. Join one of the expat clubs and do charitable work. Go for lots of boat rides. Write a book. Enjoy the opportunity to do the things you love but never get time to do.
b) If your husband has been invited from overseas to work for a bank, you will certainly be able to afford living here. There may be some necessary changes to your way of life (living in a flat instead of a house, using public transport more, eating out less, for example), but you will not, by any standards, be poor. The average salary in Switzerland is about 60k (if I recall correctly). Anything more than that and you'll be quids in!
c) It is desirable to learn German, but you'll get by - for the first few months, at least - with a phrase book, your index fingers and lots of lots of shrugs and smiles. Quite a lot of people in Zurich speak English, and many of them love an opportunity to practice. Just be sure to learn 'Sorry, I don't speak much German', 'excuse me' and 'thank you' before you arrive. The rest will come with practice.
Good luck!