In all honesty, I don’t think the location will matter much as a recent graduate. In fact, I think you’ll be extremely lucky if you’re managing to make a real living in music just out of school, much less making enough to be able to pay off school loans on top of that. LA may be a bigger market but competition will be tougher and cost of living higher. I think you’ll make good contacts at Thornton that may prove helpful in finding opportunities but, in the popular music world, no one’s going to care that you went to USC vs UT. It’s about your playing.
USC will meet need and I agree with SpiritManager, I think you will get financial aid. The NPC is the “net price calculator.” It’s a tool you can find on the USC website that estimates your cost to attend USC. I suggest you run it – it was pretty accurate for my son.