Alright. Here's my story. I joined the Army after getting my Bachelor's degree (two, actually) as an enlisted soldier. I'm currently working on putting together a packet to go to OCS and get commissioned.
A few thoughts.
1. On a degree
Get your degree first. You are obviously headed that direction anyway, but go with it. Get your degree. Don't count on the military to take care of you.
2. On ROTC
One of my buddies here did three years of (Army) ROTC. It's pretty basic. You take Millitary Science classes along with your other classes. Your first two years carry no obiligation. As a junior, you have to start getting serious about it. There are summer training camps and other stuff. Eventually, you will have to commit to commissioning. If you take no money, I think you can change your mind at the last minute. If you get an ROTC scholarship (useful), you are usually obligated to either pay the money back or serve as an enlisted solider. I'm not sure which. Find out if your college offers Air Force ROTC, track down their information, and contact someone in the ROTC department. They can give you more information.
3. On electrical engineering
I don't know too much about the Air Force. But I know they place a lot of weight on technical degees. I thought I read somewhere that to become an officer you either MUST have a techinical degree (math, physics, engineering, computer science, etc) or if you don't have a technical degree you are kind of at a disadvantage. Research that more because I don't know anything more than that.
4. On a Master's degree
Yeah, the military pays for some graduate degrees. But it is usually something that is advantageous to them. For example, if you will go teach at a service academy or are serving in a very technical job. If you are a finance officer, they aren't going to send you to get your Master's in EE on the military's dime. Also, there is usually at least a one-to-one service obligation for schooling (i.e. two years obligates you to two years of service). Dannyboy made a good point that you will also probably have to have a few years time in service and be promoted a few ranks before they military is willing to invest in you.
5. Other thoughts
It would not be a bad idea to be an officer. You will be taught more and expected to take more responsibility, you will be paid better, you will be treated like an adult, and I think it is generally a more beneficial experience. Esp over a shorter term. If you stay in 20 years, things even out, but I think it is in all ways better to do three years and come out a lieutenant than as an E-4 (give or take). I am probably going to piss off some of the senior NCOs that I know frequent this board, but that's the way I feel.
Like fistful said, be sure you want to do it. The Air Force has less responsibility over here than say, the Army, but you may be deployed to Iraq or Afganistan. You may be stationed somewhere you don't like. You may be stuck working long hours. You may have to work for an idiot. But you can't tell them that because that's UCMJ.
There is a lot to be said for being in the military. As much as I hate the Army, I've learned a lot, it will benefit me a lot, and I would always have wondered "what if?" if I hadn't joined up. But be ready for what you will have to deal with and be prepared to stick with it.
Final thought. Check out this
website. I found it very useful when looking at the Army.