L.D.
I think you should do your yoga workout anytime of the day that works for you. For me that seems to be in the evening. You can eat before doing yoga but I would suggest keeping it really, really light and try to stay away from drinking orange juice and coffee before you exercize. I would probably just eat a piece of fruit, do my yoga and then eat a full meal.
The company Gaiam makes some really great quality yoga DVDs. My favorite instructors right now are Seane Corn and Rodney Yi. You can pick up the DVDs at Target.
I think you will really like yoga once you start it. I've found that it's a physical exercize but it quiets the mind as well, which is really nice when you are someone like me and is always thinking about three things at once.
Enjoy.