It all depends on the actual location of your aneurysm. Mine was on the top/centre of my brain, and my scar was 10 inches long, with 55 staples and three stitches. It went from the top of one ear right over the top, to the top of the other ear.
I think your aneurysm is at the base of your brain (?????) so it would be different for you.
The amount of hair that they shave would also depend on the size and location of the incision. They took a strip about 2 inches wide right across the incision line. What I did find however, was that I lost a lot of hair about six weeks after the surgery. I would wake up, and my pillow would be really dark with lost hair. Could have been the surgery, could have been the anaesthetic, could have been stress - or a combination of all of them.
Pain-wise, it was better than I thought it would be - they kept me pretty well dosed up for the first ten days or so.
I was in ICU for three days, and on a general ward for another ten, and my surgeon told me not to rush back to work. I was lucky enough to be able to take six monthes off work. I had some cognitive issues, early in the piece, but I was good after the six months. I also have multiple sclerosis, so that may have slowed my recovery down.
Don't be surprised (although it will drive you nuts) if you find your 'processing speed' dramatically reduced, have trouble remembering things for a while and get confused in areas with lots of lights, noise and movement (like shopping centres, parties and stuff).
It is normal, but it will come back, just be patient and remember that if you push yourself, you will pay for it in headaches, fatigue, and even more confusion.
BUT it WILL get better - you might not notice it, but one day, you will think wow I am so good now!!!
Some people have few problems, and get back to work and become fully functional much faster - but far and away the majority of people I know (who have had this surgery) would agree with me.
Kind regards, and let us know how you are going