Legal Question in Intellectual Property in California

These are two different subject matters. Your compensation is a contract issue that can be dealt with in civil court or small claims. Copyright is an exclusive federal matter that must be dealt with in a federal district court.

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That being said, if you go to federal courts, you can join your contract claims since it is against the same defendant. It is allowed by the federal rules.

Were you an employee or an independent contractor? If the former, go to the Labor Commissioner rather than court. You may be entitled to additional damages. If you were an independent contractor, small claims would be suitable for a breach of contract claim if you'd be satisfied with $7,500 or less. If you had posed a valid U.S. Zip code, I could give you a Labor Commission office location near you.

A suit for copyright infringement probably should be tried in the United States District Court, since your best remedies are available under Federal law. You'll need to file an actual copyright before filing suit. State courts might be able to give some kind of an award based on common law principles, but that's playing a weak hand.