For the tolls: very few roads in California assess tolls (bridge tolls are much more common). And it is very easy to go between LA and SD without using the toll roads.
For valet parking, you typically drive up, give the keys to the valet attendant, who gives you a claim check to be used when you are ready to leave.
If the valet service is chargable (more so at restaurants) you typically pay when retrieving the car, although this can vary. Tip is given to the attendant who hands you your keys and seats you in the car (the staff typically pools its tips).