I was down there in 2005 during the Falklands winter. I guess you don't really need anyone to tell you it's effin cold down there, so yes, take plenty of warm clothing. Take as much of your CS95 warm gear as you can fit in your bags, norgies, fleeces, even your long johns (if you still have them).
There's an education centre, running all kinds of courses. Like Boarderlyne says, it all depends on who else is down there with the Qs to take the classes but when I was there we could do a course in mig/tig welding, 4x4 driving courses and other things like that.
You should get a voucher for 2 days Landrover/Pajero hire too, I teamed up with a mate at work and we took our r&r at the same time to combine the vouchers and had a massive Pajero for 4 days, we just went off around the island exploring.
The food is good, I never thought I'd say that about a military mess, but I thought the food was great.
Gym, you can't say enough about the gym facilities down there. They're amongst the best in the military. There's also a massive 33 metre pool which is really nice when you've been out and about all day. Even the short few minutes it takes to travel from the accommodation to work can chill even the brassiest of monkeys.
Accommodation, single man/woman rooms when I was there. I've heard rumours that they're starting to renovate/replace some of the jr ranks corridoors and for that reason they're sticking 2 peeps to a room for a short while, no reliable source for that gen though so don't take it as gospel.
I'm not a pers admin, but from my experience back in '05, they did seem to be open "for the public" at fairly strange times but that's the norm these days, at any camps PSF. PSF was up at the top of the hill opposite the Airhead/airport (whatever you want to call it) terminal, but might have moved since I was there.
Should be good, at the end of the day, at least you won't have to do any bullet / mortar / rocket dodging. Cushy det in my opinion, only thing to keep an eye out for is sheer boredom. You can solve this by a few things if you make an effort, but the 2 most popular "extra-curricular" activities are the Gym and getting smashed on ale.
Hope this helps