"JCP, I want to know what the probability is if he signs up for either the Guard or the Reserves, that he will be called to active duty in Iraq."
~ That all depends on his rating.
"He does not believe there is any chance he will be called to active duty prior to college graduation. From what research I have done, it appears to me that the chances are very likely he will be called up to active duty possibly even before he enrolls in college as he is 17 now and will not graduate high school until next year (by that time, he will have completed all his training if he signs on now as they want him to)."
~ You don't explain the circumstances of his either enlisted or commission, and I can't comment based on the above paragraph without more information.
"I was wondering if it might be better to achieve his goals in the long run if he completed college first and then enlisted."
~ If he graduated from college first, he doesn't have to enlist, he can apply for a commission. Still, it all depends on one's rating.
"Also, is the training for the Guards and Reservists as tough as the other branches (I would hope it is) in preparing to participate in war?"
~ I don't believe the National Guard requires bootcamp, but a minimum 2 week training course.
"I'm wondering, too, if the Guards and Reserves are badly stressed as a result of the war as mentioned in the original post (more seriously stressed than the other branches of the military)?"
~ I don't believe so. Tell that to the regular grunts on Iraqi soil.
"I feel like I'm handing over his life, you see, and just want him to make the most informed choices he can rather than to be coaxed into it by the big sign-on bonuses, kickers, etc., that the recruiters are offering."
~ Maybe you should trust your son and his own decision making. I made my own decsion at the age of 19, without any interference from anyone.
"Thank you for your years of service to our country, and for being willing to answer my questions."
~ You are welcome.
"Melvin, the best thing you got going for you is your willingness to humiliate yourself."