I don't remember the exact laws in California, but I do know this. You can't be a 1099 unless you have a bunch of stuff in place. For instance if you get all your business from 1 source good luck of not being in violation. They will see you as an employee. They expect the Prime to take care of your insurance requirements. They way around this is having multiple contracts that no one source is your primary source of income. It was really hard for me to get GL out there since they look at it all different. I have always had multiple sources so having 1 company paying for my GL would have been out of the question.
As far as piece rate is concerned you can still get paid piece rate. You are still required to make min wage and anything over 8 hours is overtime. Don't forget to break about every 3 hours. You get two 10/15 minute paid breaks and one 30 unpaid break that has to be taken within the first 6 hours.
So there are some ways to do a work around. A lot of Grey in California.