If you'll allow me a moment of self-advertising, my company sells a version of Wine called CrossOver. It has a user-friendly wrapper, so you have less fiddling to do with files and command lines. We contribute all of our improvements back to the Wine project and are the largest force driving Wine's development (check out the email addresses in the Git log). Working on Wine is my full-time job. Even if you don't end up using it, purchasing our product directly helps improve Wine :)
Yes, for many games, but not for all. Older games tend to run at full speed, more modern and cutting edge titles tend to run at a 20-50% framerate reduction. Even some modern games run at full speed. It really depends on the game.
