You have to make sure that the car can pass both emission and safety inspections. be cautious cause some sellers and dealers take out the bulbs on the CEL and once u buy it. after a few miles it turns on. And then you have to pay for the trouble to find out the problem.
Register is i believe $65 1 yr and 120+ i think for 2 years
then you have to insure it. or actually have the car insured already.
Some places in DMV require a BILL of Sale. Some don't and just need the title cause you need the title under your name unless its from a dealer