the commute from carlsbad to kearny mesa isn't so bad. you can take the coast highway until you get into del mar, and then cut over to either 15 from 56, or take 805 to 163. depending on your shift...
It's a small difference in pay. Maybe a couple thousand a year. Rent in the bay area is up, since no one can afford to buy a house, but the hospital pay somewhat reflects
$2500 is more than enough. Look in neighborhoods like the panhandle, noe valley, castro, and the mission district near delores park. All are safe, and reasonable. The panhandle is very close to UCSF...