Have you popped your head into a recruiting office I would seriously go there and get a fist full of info first. The trouble with forums such as these they tend to be a scathing to any questions asked and you end up with being told a load of tosh. Anyway....
OOW on submarines - yes you'll get loads of experience.
Ops room on a boat is the control room as for what a Warfare Officer does at attack teams (if its still called that) I have no idea.
Do you have a choice as to which boat you go to? Probably not, but you can ask, it is usually depends on what they are short of at the time and where. You have to remember that they are trying to man ships/submarines not pamper to everyones wishes.
Is there a difference between a SSBN or SSN, ermmm well think of a SSBN as a SSN with an extra bit in the middle for the missiles!!
As for roughers under the waves all I can tell you is that when I was on Otter, OK so she was a piddley little O boat, we were of Iceland at 300 feet and it was as rough as a b*****d. Yes you can feel it sometimes dived!!
Good luck with whatever you do.
As X(SM) you will almost certainly get time on both, the main reason being that it is no good getting to Perisher and only having done SSBN's as much of the course content is SSN orientated, you need an experience of both approaches to be a useful wafare officer at a later date.
As well as the watchkeeping bit you will also have a department to run, so in all your spare time you will be able to do that. In my time I variously looked after the casing (not as cushy a number as it sounds) the fore ends and the torpedos, the ships office (I can now type with treee fingers) Sonar and Ops/Navigation. Personally I was always non SSBN, but I did know people who prefered the SSBN lifestyle, though some have problems readjusting to real life when they need the attack boat time to get on their perisher.
Being Officer of the Watch (manning the bridge in the fin) Giving Conning Orders, Recieving Fixes from the guys on the plot table (which surfaced on a T boat is Warfare Senior Rates and qualified Leading Hands) and making adjustments to speed/course etc. Being officer of the watch below. Generally the Junior warfare officers will keep 3 or 4 hrs a watch on the bridge depending on how busy the watch leader is or how many qualified OOW there are in the watch ( the watch leader TSO/TASO is generally a senior 2 ringer or two and a half.) When stood down they generally do divisional work or work associated with their jobs CASO/CORRO etc or whatever the XO has stitched them with.
Generally there will be 3 warfare officers at one time in the control room depending on what is going on at the time. The Watch leader (TSO/TASO) and two junior officers alternating manning the plot and the persicope.
Warfare Officers Man the plotting table, putting fixes on the chart from GPS/SINS Etc. Running the General operations plot. At periscope depth they man the search or attack scopes alternating between that and the plotting table. Rarely they will be qualified as Ship Controllers and do stints on there as well but that is fairly rare they normally qualify then avoid it like the plague. When fast and deep they may relax down to two officers in the control room so one can get a brew and do some work again and cycle round like that.
Generally boats roll like pigs on the surface and PD in rough weather but you get used to it, deep not so bad, depends on the depth and sea state.
Career wise you start of in a non job like TORPs officer, once you get your dolphins the dizzy heights of Correspondence/Casing/Classified books officer await. Steadily moving up the pecking order to Navigators course and back to a boat as a Navs/ N2, then Advanced Warfare Course & back to a boat as a watch leader, On selection Perisher then back to a boat as XO then finally CO.
Generally in a good year on a running SSN you might get 3 or 4 runs ashore, bad year none. had more had less depends on the programme.
Join up, 8 months dartmouth then Initial Fleet Time. Then a Base Liaison Visit, then the first part of ILOC then a few months at sea as an Asst Logs Offr - learning basic pussery. Then finish ILOC then off to first complement job. Then you will have to tick the following boxes as a Lt. Sea Job - SM/Skimmer/Droggy Vessel or if unlucky a flat top. Also a Sec/outer Office job. The other options a plentiful: DE&S jobs with some IPTs, jobs with the booties - CLR, 3CdoBdeHQ. Logs Spt Jobs at the waterfront. As you gain experience there is specialist training such as Barrister and CMA (Management Accountancy) also can get masters in Logs/HR and other stuff.
If as an SUY then you will do less time at BRNC then will slot into the ILOC part.
How much do you want to know... and guessing by your ID I guess you are a Royal?