Most all of your questions are personal opinion, so really its up to you. Personally, I much prefer using GNU/Linux to any of the Windows offerings, but again, that's just my personal opinion.
Are you a patient kind of person? GNU/Linux won't hold your hand much when the going gets tough, you will however find a massive amount of good documentation and a large community of people who are mostly willing to help.
Why not start with something like Ubuntu and see how you go? Its probably the most straight forward install with that will likely give you the least amount of trouble once its installed.