I have tried this diet for the past 4 weeks and I personally love it. I usually fast once a week on Sundays (also my rest day for exercise), so I can't give you much help on whether or not you should fast after exercise. I think Brad Pilon, the author suggests that it shouldn't have any adverse affect if you don't eat before or after exercise b/c fasting releases GH anyway and wouldn't result in any muscle loss.

But I do find this much easier to conform to. I don't mind not eating one day and then getting to eat like a monster at least 3 times a week to make up for the calorie defecit. I felt better and much leaner although my weekly calorie intake was higher on average than normal. I actually tried to NOT do it this week, but ended up fasting today rather than Sunday. I just like this style of eating better.

Good luck to you. I hope you experience all the benefits I have with IF.