My info is even more outdated, but he should have been able to leave base on weekends from the time he got to Charleston. However, he has to wear a uniform when he goes out on the town for the first several weeks. If you get married during A School, I believe he will be able to live with you in base housing or off base (I'd recommend base housing, you won't get BAH, but the commute is better).
When he graduates Power School, he will be on hold, waiting to class up for NPTU, which could be a while, depending on his rate. I don't know how they do it in Charleston, but in NY, the hold students typically work staff hours: 8-ish hour days, rotating shift work.
I've been in the navy for 17 years, I know a few guys were married when they came in and their marriage survived. I also know guys who were in serious relationships when they came in, theirs didn't. I've been married for 8 years, and still counting, so it relationships can survive this job, but it takes a lot of work and communication. Remember, even though his hours will suck for the next few years, your future husband will still come home every night. When he gets to his ship/boat, not so much, and that's when things usually get tough, but like the last post said, it's worth it.