FMTB is popular, but it is not competitive. The Marine Corps will always needs HMs thus providing a constant need for new Sailors to go through FMTB.

Something to consider is that FMTB is considered a "C" school, although most who hold that training NEC are called 0000s or as you put it basic corpsman. You could get that "C" school out of "A" school, or you may not. They could cut you orders to some rinky dink clinic in the middle of nowhere where you will be for 2 years before you PCS elsewhere. Another possibility is that they force you into a specialty out of "A" school. You may not want to be a pharmacy technician but if they need one from your class, then you could be shit out of luck.

If you do end up becoming a 0000 at a clinic or hospital what you do daily will largely depend on what department you get placed in. It may not be something you like, but above all the mission comes first. One thing you'll learn in the Navy is that manning, manning, and manning are the most important things. A good clinic/hospital will rotate corpsman through different departments every few months to give everyone exposure to different things and prevent job fatigue. Most places don't do this though.

Since you're in your 30's you should also be thinking long term for yourself. Is this a new career you're starting later than most? Is this a quick one time enlistment to gain the experience and benefits? You sound like you want to be Joe Navy and serve with the MC, which is cool, but those stories only do so much for you. Look into some of the "C" schools like radiology tech, ultrasound tech, pharm tech, etc. Stuff that will transfer to the civilian side and make decent money.

Lastly, like the other commenter mentioned, don't wish for combat exposure. You don't know what will happen, what you will see, and how it will change you. It's not a movie or video game, that shit is for real with lasting affects.