OK, TONS of great information added since my first $.02. Not really much to add especially since you are now steering towards an SF MOS. I'll just add a couple more bits of perspective.
1) As I mentioned, I got my degree in Mechanical Engineering. Worked my ass off for it like all Engineers do and had to repeat a Calculus class or two along the way. I passed my EIT in the Fall of 1995 and headed off to Officer Basic School never to do an integration again. After 2 years running around ADT, I went into the guard, caught the flying bug (part of the reason I went military to begin with) and started building my time for my "dream job." Now almost 20 years later, my "dream job" has turned into a sort of nightmare and all my friends who are engineers are making a hell of a lot more than I, spending every evening at home with their kids, and have been able to lay down the roots that guys in the AD side of the house just can't do. In short they have the stable kind of life that a 40 something with kids needs to have. But the suck of the matter is - my Engineering Degree is WORTHLESS today. There is no way I could get a job as an engineer now so in essence, all that hard work went down the tubes. Keep that in mind. You have mentioned that if you went AD, you would plan on returning to an engineer career, but if you are out for long enough time, there may not be any going back.
2) I have a couple friends that tried out for our local ParaRescue Guard Unit. Although they were technically part timers, the amount of time they had to spend for the training required to make it into a National Guard Special Ops unit was essentially a full time commitment. Others here are far better qualified to tell you just how hard the training will be, but it will be far from a walk in the park. In the end, one of my friends got injured and hung it up and the other decided to get out and concentrate on his Chiropractor business instead. Both were top notch guys. Not at all suggesting that you won't make it, just telling you that there will be a lot more commitment required than most people could ever realize.
I know that my posts have been kind of "glass is half empty" with a lot of warnings about the pitfalls on the route you are contemplating. But know this, going into the Army was the single best decision that I have ever made and would do it again (although maybe a little differently).
I am kind of curious, what do your parents think of your going into the military?