Hi Wind6--
Hello to a fellow Illinoisan. I'm originally from Chicago, and you will be in good hands at Northwestern (a great hospital and medical team).
I did not have much trepidation about the head frame but understand why some might. Overall, the experience was anti-climactic, which was a good thing. They will, at a minimum, numb the areas before applying the frame, and they would likely give you some antivan or something similar upon request. But as Arizona Jack suggests--be sure to ask how they will approach it as it's not done the same everywhere.
The treatment itself is quite quiet. The frame is the most "dramatic" moment, and the rest of the experience is fairly smooth.
I encourage a companion to drive you back to Springfield, but the worst part of the at 3-hour drive will likely be negotiating Chicago traffic as you depart! But I did a 4-hour drive the day after my treatment so it is possible but not advisable. I suggest staying over in Chicago (I was required to stay the rest of the day for monitoring) the night of your treatment day. Gain what strength you can!
If you have more specific questions, feel free to PM me, but I know you will do great!! All the best on the 10th!!
P.