Alcuin is supposedly very quiet, but it's also pricier than most. Langwith and Derwent are old, along with parts of Vanbrugh (Eric Milner and Wentworth E definitely) - on the website it'll tell you when the accommodation was built. As far as I know, Langwith is moving to Hes East next year though, so the current Langwith will become Derwent (if that makes sense).
Both Halifax and the older parts of Vanbrugh seem to me to be the noisiest, though I know nothing of James.
Most colleges have bars of some sort - Langwith's is pretty popular, Vanbrugh's is pretty rubbish. The others I'd guess are somewhere in between, though I haven't spent much time in them. I don't know if Alcuin or Goodricke have a bar, though. Most people I know don't restrict themselves to their 'own' bar, they just go wherever they feel like (all this said, I don't spend much time at all in the campus bars, so someone else will probably be able to give you better information).
I currently have an ensuite and it's just really nice to have the convenience, and if you can afford it and don't feel like you'd be wasting money then I'd definitely go for it. That said, I've heard that shared bathrooms aren't a problem, and I think they're cleaned daily (or at least very frequently). Showers per floor/people per shower ratio depends on which college you're looking at, the website will help you with that. As for noise, ear plugs are a fantastic investment
I live in New Vanbrugh and for the most part I don't think it's too noisey to be able to work - it's often the loudest when I have essay deadlines
(though I think the library opening hours are changing to 24/7 next year, so if all else fails you can just stay there
)
I know very little about catered accommodation -
this page might be of use to you, it states that if you miss a meal you're not entitled to a refund, so I guess you're supposed to turn up to all of them if you want feeding.