I recommend using VMWare to get your feet wet. This way you can try countless distros to see which one suits you best. Ubuntu and Suse are good for newbs. Plus, you can do all your gaming right next to your virtual machine. Best of all, though, is the fact that you don't need to go off partitioning your drive a million times and deal with dual booting. Trust me, if you care about gaming at all you are going to want to boot Windows in some capacity making a dual boot a necessity if you are going to run Windows.
Sorry for not actually answering any of your questions.