Yeap! True. From what i heard/research on the web ... residence is less happening and more quiet. So it's alot more conducive for studying. I think they too have study clusters?
Not too sure about halls though.
Hall, i think it really depends on which hall and what kind of neighbours you get. It can be very rowdy especially if you are surrounded with socialites and LOUD people.
Personally, for me i'm applying for PGP as my first choice. I don't really wanna get bogged down with too many activities. I suppose those seniors jolly well how the atmosphere is like in NUS. So yeah. Just spend your time with some decent CCA ... party once in a while ... but study well at the same time.