As for pay you have the potential to start at $1,700 a month and the rank of E-3/Seamen (which actualy would go along with your rate, so if you were a corpsman it would be hospitalmen, Aircre would be airmen etc.) This of course all depends on what credentials you have prior to enlisting such as college credits, volunteer service, jrotc, etc. If you start as an E-1 you which is the most basic you'll be making $1,300 for the fist 4 months than about $1,450 then on.
If your going to do it I reccomend learning naval terminology, ranks, and your 11 general orders. I'd also start doing a lot of conditioning, they're looking more for endurance then strength.