I was hired jan 1st as a salary employee making xx,xxx per year with a signed contract. In Sept. I recieved an e-mail that they were going to switch me to hourly.... they did nothing until November and then switched my pay without warning or asking me to sign a new contract... does this mean they illegally switched my pay since the only formal contract they have signed is the one for being a salary employee?

No one on this website can comment on a contract that they have not read. You are probably going to have to pay a lawyer in California to read the contract.

In CA, prior notification is a must at-will or not.