1) In the vicinty of UCSD rent is expensive because La Jolla is a very high end place. I was paying 600 to split a room. Try Kearny Mesa, Mira Mesa for more affordable living.
2) On campus is really nice, good for having making close friends because the campus is so huge.
3) Not too sure tbh. Sorry.
4) There are jobs available on and off campus. Lots of research lab tech stuff going on and there are EMT jobs available too if it fits with your schedule.
5) Social scence is great, mission peach, pacific beach, downtown all have some awesome clubs many with no cover charge. Lot's of music venues. Lot's of art. If you're feeling hipster-ish and want to try some awesome and unique bars or restaurants I would suggest going to North Park.
6) It's fairly easy to talk to professors but remeber you're in a class of 100-300 hardcore pre-meds who all want those 1-2 slots. It's better to do your own research within a division you're interested in (radiology, anesthesiology, etc etc) then look up who is doing active research 9easy to find on UCSD's interwebs) and email them directly with a CV. that's how I ended up doping my research.
You can PM if you have any more Q's. I'm a native San Diegan.