Welcome Mesinan, I figured since no one else has stepped up to the plate I'll go ahead and try to answer your questions:
1. Pro's and Con's of the field
2. How hard is it to be a woman in the field?
3. Is it possible operate exclusively on brains? Do I need a fellowship to do so?
1. Pro's: This is one of those fields where you have to love what you do. If you love neurosurgery than the biggest pro is being able to operate on someone's brain/spine, and have the potential to change the course of their life for the better (or as a con, the worst). Other Pro's are that neurosurgeons tend to be well respected and fairly compensated. Also, you get to use some cool instrumentation and technology.
Con's : NSG residency is probably the most demanding residency of medicine. The hours for your career will continue to be long, especially if you do not live in a big city. The smaller town neurosurgeons usually end up taking some extensive call (although they might not end up going in overnight that often). Because of the high acuity of the patients, you will be under higher stress and subject to more scrutiny than your colleagues (ER docs, hospitalists).
2. Talking to one of my female NSG attendings, she always commented on the fact that not only did she have to be a neurosurgeon in residency but she had to work harder than everyone else because she was routinely written off. There are not many women in neurosurgery and as such I would imagine that increases the stress associated with already stressful training.
3. You do NOT need a fellowship to operate on brain only, however as has been alluded to previously, this is simply not feasible in private practice. That being said, if you work in academics or are part of a larger group, it would be quite possible that you could operate almost exclusively not only on brain, but subtypes such as tumors, aneurysms, or functional brain surgery(deep brain stimulators for parkinson's etc,). That being said, this setup would almost certainly require you to be fellowship trained to be hired on in such a position in academics.
Take everything I have said with a grain of salt as I am only an MS4, however, that represents some of what I have picked up about the field thus far. PM me if you need anything else.