EMT since 1990, got my EMT-I in 94 and my medic in '09. One year private EMS, did four years in Brooklyn and been at my current EMS job since 96 alternating between the street and training. HM2 USN-R from 98-06 with a Marine unit. I went to medic school 3 times. A post 9/11 deployment knocked me out 8 months into my first go round in '02. Cancer knocked me out in 05. I finally started and finished the 14 month school in '09.
To your main question. Work wise the school is demanding. Med math, cardiology, pharmacology, medical terminology, college level A&P 1&2*, and numerous other areas are like new languages, ways of thinking or skills sets you need nowhere else. Time wise with classes, ambulance rotations and clinicals it is profoundly consuming. Add in the study hours outside all of that.
After you get your EMT most programs require 6 months or more of full time EMS work experience. Some don't though. Some will also require the National Registry EMT cert which may be independent of your state testing you did to get your original EMT cert.
*Some states may require A&P 1&2 before you get admitted to a program. Other let you take it while you're in medic school.
Like police work and FD work it takes a unique dedication to do the job. It sounds like you'll be admin as soon as you graduate. But many states require patient care/contact hours to maintain the cert and you may need a part time EMS ob to do that. Quizzes, tests and exams are easier to pass as a student. It's then reinforced with the work you do to firm it up. When recert/refreshers come that when you need to reach back to your experiences and knowledge base to get through the state/National Registry tests. You'll need to maintain ACLS, PALS and CPR(and maybe GEMS and PHTLS) certs which expire every two years. As long as your employer pays for them you're golden. But if you haven't unsheathed a needle, paced a cardiac patient, hung a dopamine drip, performed an RSI or two, ran through your ACLS protocols and pronounced a patient, or done a Parkland formula you may find keeping the cert really difficult.
If you're gonna jump into the biz do so ith both feet. There's nothing worse than the line folks looking at their "leader" who's barely every touched a patient or pushed an ambulance for a living spec'ing their gear, telling them what they'll work with and how they'll do it.
More so, are you ready for blood, gore death and suffering? Are you ready for the chance to be exposed to Hep C and HIV? Needlesticks, being bled on, assaulted, and vomited on are part of the job. Lifting obese patients, crawling into wrecks and that could all be in just ambulance time and clinicals inside of a few months. Are you an empathetic and compassionate person? Do you have a well developed coping mechanism? That dedication is needed to push yourself through medic school.
Good luck.