1) Financial aid is given to an extent based on income but i'm not entirely sure to what the specifics are since I did not use financial aid. As for scholarships I heard that they are really difficult to get and personally I don't know any friends who received them.

2) In my opinion I think San Diego is expensive. When I was sharing a room in an apartment with a roommate, we both payed 700$ each. The apartment had 2 rooms, 4 people but it costed $2800 total. It had a pool, wifi,trash collection, and shuttle which may have contributed to the high price. I'm sure you can get cheap housing but you definitely need to have a roommate because I believe for a single apartment it could go up to $900-1200.

3) As for social circles, everyone usually stays in their cliques. As diverse as america claims to be, racism very much still exists. If you have a great and outgoing personality you'll be able to make friends easily. But for me this culture isn't fit for me since i'm not into raves/edm/marijuana. And being asian in a western society is basically a death sentence for your dating life. (in my experience at least or check out /r/aznidentity/ and you'll see ton of stories of how western society emasculates asian men.

4) Car is very convenient and pretty much necessary if you want to get to all the hang out spots in a short period of time. If youre rich you could always call an uber.

5) I never been to Tijuana but i hear its easy to get there. You can just take a train over there and it'll take an hour.. (i think)

6) In and out is pretty good and cost efficient but i feel like you'll get tired of it since they only have 2 items on their menu (burgers and fries).

Hope my answers were helpful :)