My question involves employment and labor law for the state of: California

This is 2 part and i was hopefully going to conserve space with combining.

My employer requires after hours work to "babysit" equipment at a sporting event and be on call in case of the machines needing assistance.
My employer offers "comp time" in exchange for such services.

Is this legal? Should the "comp time" be paid in time and a half increments?
Say we have to "babysit" for 3 hours should we get 4.5 hours off in regular time?
Sometimes there are errands and such that we need to do which are necessary during normal hours and this prevents having to take time off.
But what should the legal way of doing this be?
The after hours stuff is usually starting at 6:30PM and running until 10PM or 10:30PM.


Secondly as for mileage.....
The employer is now using "mapquest" to see what the mileage from 1 customer to the next "should" be and deducting the excess.
Is this legal?
Are we expected to know each and every customer and the very most efficient method of getting between them?
If we vary by 1 or 2 miles shouldn't this be let through?
If the difference is excessive i can understand a discussion, but changing what we entered seems wrong.
I will agree that we should know the best route from home to the office, but for every stop we can make?

If anyone can help with law numbers or links to them it would be most helpful.