Do cruise ship crews always live aboard ship?

The crews aboard a cruise ship are under a contract for a certain length of time. At the end of a particular contract they can go home. Our waiter was from the Philippines; our room steward was from Czechoslovakia, etc. Our room steward was heading for home 2 weeks after we returned to port.

I can't help answering this in another way:
During the actual cruises, yes, the crew lives on board. They do not work from 9-5 and at the end of their shift, step outside, head to the "garage", get in their little sail boats and head for shore.

Yes. They also get room and meals in addition to their pay. Length of contracts depends on the nationality. There are Manning Agencies in various countries that offer personnel for the different positions. A Philippine crew member employed by a Manning Agency in the Philippines will have a different length contract than someone who's comming from an Eastern European Manning Agency, and so on.

The accommodations will vary depending on position or rank of employee. Generally, unless you're an officer or shipboard entertainer, you will have to share a room. Officers will have cabins somewhat similar to those of the passengers and on the passenger levels. Non officers are usually below deck. FWIW, in general, only officers, entertainers, gift shop and pursers are allowed in passenger areas when not working.

While they are on the 'Season's trip' [contract is right], they do.

Crews "Change out" so that they can get 6 weeks off, and get back on, or transfer /change out to another ship.

I like the user's answer with the little ships that wait outside and take the crew home. why to funny.

Most of the crew lives blow decks as they say, but their are cabins scattered around the rest of the ship that houses the captain, officers etc. Most ships have seperate facilities for the crew.. . dining rooms, bars lounges etc.. much of that depends on the size of the ship, and what the cruise lines want to provide to their staff. Lengths of service contracts usually depend on the cruise lines as well as the positions held. Staff may choose to stay on through 2 contacts before every coming off, some will take their holidays between contracts.. but again, it depends on what the cruise lines offer.