As far as your question re: Slimming Formula vs Performance Formula, I have used both and they do different things.
Both will give you more energy but in different ways. The Slimming Formula would be my recommendation (for your goals) of the two. The Slimming Formula helps to speed your metabolism but you HAVE to workout or it's really no use. The higher metabolism is what makes you feel more energetic (but not at ALL jittery).
But, here's the kicker and not something BB is claiming for the product but what I have found from talking to several people who take it and my own experience, the Slimming Formula also helps reduce sugar cravings. Don't ask me why but whenever I stop taking it (stopped during a move recently because I stupidly packed it and couldn't find it!:rolleyes

I begin craving (& usually eating) sugar and white products. When I began taking them again, the cravings were gone and I could take or leave the sugar. This is coming from someone who is hypoglycemic (chronic low blood sugar) and sugar is like a drug for me! :eek:
The Performance Formula helps your body use oxygen more effiently. I took it the first time before a run (I don't run) and didn't even breathe heavily after 2 miles! It transports the oxygen to your muscles so that they can work harder and longer without fatiguing.
Hopefully that helps you decide between those two products. As far as the meal replacement, I can honestly say (after trying and using both) I like Shakeology as a meal replacement (nutrition and taste-wise) than the regular meal replacement. And, yes, use either for one meal a day.

"Eating to fuel your body's needs" can also refer to eating more protein when you're trying to build muscle, eating less on the days you don't work as hard. You'll learn to listen to your body in the first few weeks and know when you are really hungry and when you're just eating emotionally or out of boredom.
I wouldn't do the 2-day fast at this point (unless you really want to). You'll find yourself worn out and tired. It's just to prepare your body for the changes to come (sort of clean the system before making changes). You can also do the same thing with 4-8 oz protein shakes mixed only with water and take a multivitamin (which you should be taking anyway!)
I know this is a lot of info (sorry) but hopefully it helps you get started!
Tina :cool: