When a ship goes to sea with it's optimal compliment, meaning, full(and this doesn't happen all the time) in a one in two rotation(7 hrs on, 7 off, and then 5 on, 5 off) the sonar section will have maybe 10-12 people in it, in a perfect world, with half of them on one watch(shift), half on the other, rotating every other watch through the day. The section will obviously have people of varying ranks and qualifications, I'm sure you'd expect that...
Where you get posted at first, all I can say is, "it depends". I'm from Halifax and made it clear when asked about the 1/3 point of my 3's course I wanted to come back home. If I hadn't have been from here, chances are I'd have said just leave me right in Victoria, as it is nice enough out there and A LOT of guys fall in love with it their first weekend after arriving from basic. But there is never a guarantee. You'll go where you happen to be needed at the time. They'll try to send you where you ask for, but ultimately, as they like to tell you, the military's needs come first...one thing though, whatever coast you ask for, you can probably stay your entire career on that coast. the only thing that might change that is YOU asking for the posting to the opposite coast. i see that once in a while.
Been in this trade since 03, sailed in 4 different ships here on the east coast since. working in a shore billet for the past year--recharging my batteries so to speak because before that, i was posted to ships and had sailed a fair bit. I went to sea for varying lengths of time...from a one day sail to three major deployments that had me away sixteen months(not all consecutive), and many shorter sails in between. depending on the ship's schedule and their state of readiness, you'll get to have countless little trips to longer, neverending ones. I can never say that any one trip's length falls into an "average"
Keep the questions coming if you see anything you haven't already. As far as basic is concerned, everyone on these boards gives their :2c: on their own experience. While there is indeed useful stuff there I try not to spout about basic as it's the only truly unique course you do, and you really have to experience it for yourself.
By the way, if you have any urge/curiousity/interest of going in the direction of submarines, make it known soonest. From what I gather nowadays, they are starting to streamline guys off directly into the sub training program. While I'm not in subs, from what I hear, it's an option that is gathering momentum.
Best,