1-you do NOT have to cut your hair! It merely needs to be in regulation...I've read at several women's forums that those who had "longer" hair actually have it easier because all they had to do was put it in a low and tight bun and it was no worries, those with short had to fuss...for what it is worth this silly myth was the *deciding* factor in my passing up a military career in my younger days! YUP, dumb huh? Read-->Women's Military Hair issues Women
2-I've had about a 50/50 reaction of support/attempt to sway me against joining from people. I realize that this is a highly personal choice and not every needs to understand or appreciate my choice, however, if they are friends they will respect my choice as I respect their differing opinion. Once someone mentions against it I respect them. Recently a new associate said, "OH my! No..." I told her that as a Nurse it is a little different, that I am going to serve our military and family.
3-since you are going to your junior and senior year at a University you may be eligible for student status Army /Air Force/ Navy stipends and what not, check into it, especially if your University has an ROTC program.
4-the age, from what I understand you CAN join before age 21.
p.s. edit to add: if your school offers NROTC, (nursing ROTC) I highly suggest meeting with them, you will be better prepared for the Officer Basic Training which is actually more like 10 weeks...let me post some links for you to check out, (this is all Army though because that is my first interest):
Army Nurse Corps
-->read for women's issues/feminine needs and training information, although, Officer basic training is not the same as enlisted basic training I think it will be helpful to read: Military Woman Issues
finally a neat site with video and information for Army Nurses:
Army Nurse Corps
If you are interested to find out about Air Force nursing I suggest a google search of Navy Nurse Trainingship program, what I've heard is that currently the training slots are filled and they will not take any new Nurses until September 2007, (since you are a junior it shouldn't affect you)