If he is undes...he gets his orders to his first command while in bootcamp. After bootcamp, he will go to a very short school (2-3 weeks)...than depending what his orders say, he will have 10-14 days leave. During that time, he can do what he wishes...it is his vacation.
After that time, he will be required to report to his first duty station. AS far as finding you a place to live and moving you...that will be all on you...unless the command he goes to allowes him a few days of house hunting leave...BUT that is up tot he command if they allow it, they do not allows. Or if the ship is out to sea, he has to go meet the ship and get to work.
Yes...odds are you will have to do everything for the move, you will have to find a new place for you to live at his new duty station. You can always try to get into base housing, but lots of times there is a wait list for that, and if you go on the wait list, it isn't like they will just hand you keys to an apt to use while you wait to get into base housing. You have to find a place to live.
No worries aobut hte move though, as the Navy has movers that you set up with and they will come pack up your house and ship it to your new duty station. MUCH easier! BUT again there is a wait time for that and it can be a month or more before they can move you.
As far as being gone for the whole 4 years...I would say he will be out to sea at least 1/2 of that time if not more. a month here, a month there, than at least 2 if not more 6+ month long deployments.
Again...after he leave is over after schoool, he goes to his duty station and gets to work.
Have you checked out the UNDES group?? OR the wifes' groups on here?