No, you are not required to have a high school diploma or GED to obtain a California real estate license. The Department of Real Estate only requires you to be at least 18 years old when it comes time to apply for your real estate license.
Yes, you are not required to be a California resident to obtain a California real estate license. As an out-of-state resident, you will have to complete a Consent to Service of Process form, and get your fingerprints taken with your local law enforcement agency.
Yes, you may still obtain a California real estate salespersons license if you are a "qualified alien". See section 2718. Legal Presence Requirements of the Regulations of the Real Estate Commissioner for a more detailed definition of a qualified alien.