In 5 days, I separate from the Air Force after over 9 years of service. Many people, at that point, are ready to keep going because you are "almost halfway to retirement". I might kick myself in a few years, but I feel like I am doing the right thing. I just can't take the BS anymore. I like my job - the actual hands-on maintenance - but the politics, the insane rules and being punished for other stupid people's mistakes got old very quickly.
I don't want to steer you away - it just sounds like your recruiter is playing on your youth and enthusiasm a bit much. Saying that a humvee is near indestructable is luring you with a false sense of security, and that you get to run around shooting a gun is giving you a false sense of excitement.
IEDs are "improvised explosive devices" - basically, items put together to blow you up. It doesn't take much to make a bomb or booby-trap. In the middle-east, it's common and cheap. They are ingenious and can be inaccurate, but that does not mean that they do not work. They use things like simple timers and melting blocks of ice as fuses for detonation, and they don't care what gets the job done. They also do not follow any real rules in combat, so the enemy doesn't care if they are using certain chem/bio agents or hunting ammunition, or even glass in their explosives.
By the way, just because there are posts in 20 different countries does not mean you will visit them all. It doesn't even mean you will get to enjoy them, or see any of them. I've stopped overnight in some hellholes, and I've stayed for months in a few of them. Then again, I've stayed in a couple of nice places - for a night or two. Sometimes you are unlucky and have to sleep in an aircraft hangar or outside at one of those places that are considered "nice" [had to do that on base in Hawaii once].
Another thing to consider is, while you are in, those education benefits don't mean quite so much if you don't have the time to go to school. Let's put it this way: depending on what your squadron/battalion/etc is like, you will probably have to plan your schooling around deployment rotations, and be prepared to re-do a class when they decide that you WILL be going even though you are in the middle of a class. At least do the smart thing and put that money into the Montgomery GI Bill when they give you the opportunity to initially sign up for it - that way, if you didn't have time for schooling and are fed up after your enlistment is up, you will have that as one of your separation benefits.
It's a hard decision to enlist, and the lifestyle is not for everybody. I really hope that whatever decision you make, that you stay safe and enjoy the path as you walk it.
Beware the recruiter - he'll tell you what you want to hear. He has a job to do, and he's probably been doing it for awhile. Most of them do it well. We'll call it "smiling while stretching the truth", and he has one goal.