According to section 339.2502a(1) of the Michigan Occupational Code, you must be at least 18 years of age to receive a Michigan real estate salesperson's license.
No, you are not required to hold a high school diploma (or its equivalent) in order to obtain a Michigan real estate salesperson's license. You are only required to be at least 18 years old and have good moral character.
Yes, you are not required to be an MI resident in order to obtain an MI real estate salesperson's license. However, you must work under a sponsoring broker who holds an MI real estate broker's license. You must also submit a signed and notarized Consent to Service of Process with your license application.