Thank-you to everyone for your good advice and encouragement. I was happy to go Navy not knowing what to expect. But everything I keep hearing is very positive. So each day I find myself looking forward even more to this new posting. (Of course things can still change until the message is cut.) How does mess life and visits to port work on ship? What are some extra duties that I can volunteer for that will help me better transition to life on a ship?
I just came off ship in September, so my experiences are fairly recent. If you want to become friends with everybody really fast volunteer to become RPO(Regulating Petty Officer... Everybody loves the RPO...
Port visits can vary by trip/deployment but usually for every five or six days alongside you will work a duty watch in foreign ports. As stated earlier departmental work and ship wide taskings can change that amount as well, but fortunately most of those jobs are a few hours rather than a 24 hour duty watch.
I have found in my experience that the C&POs(WO&Sgts) mess tends to do few organized events, but usually the members have a drink or two in the mess to make plans for the day/evening in foreign ports. After a few drinks is usually when the groups split up and head out to whatever it is they have planned(often more drinking). As I only sailed as a Sgt I can't comment with any authority on the other messes other than to reiterate what JJT said about the Weirdroom.
As far as groups or cliques in the mess break down in my experience, usually the stokers stick together(spec 2 elitism is my guess), the hull techs like to mingle(mangle) and party, CSE are a mixed bag(comm techs are nerds), and combat is usually bitter and sullen about sitting in a dark room all the time(except Nav Comms, joke lots about USB sticks and cell phones, they love it). Finally Met Techs... avoid them like the plague, very odd and they tell horrible jokes to torture you every day at sea.

PS. Remember if you have any choice, West is Best!