Thanks for your excellent questions. As member of MARS, you are serving as a volunteer to provide contingency communications to the Department of Defense, the Armed Forces and other federal and state agencies. You will need to have your parent's signature until you turn 18 years of age. It sounds like you already have the station required to operate. Once you sign up and receive your letter from HQs MARS, you will need to have your radio modified to operate in the MARS frequencies. You will not be required to move or deploy as a member of MARS. You will have the opportunity to provide communications from your home station or you may also be linked up to serve from a customer's fixed facility once you complete your training. There are monthly minimum participation requirements that you must meet: you must be on the HF freqs a minimum of 15 hours per quarter, you must submit a monthly participation report, and once a quarter you must serve as a net control station...all of these are well within your reach. Your benefits from joining are the increased operator proficiency you will gain; you will have an increased understanding of HF propagation; you will have the opportunity to participate in state, regional, and national level exercises. None of this should interfere with your school work.
For more information, I would ask you to go the Army MARS Facebook site : https://www.facebook.com/HQArmyMARS
and our public website: http://www.usarmymars.org/