I have several questions on this as well.
I've been learning the power versions of the snatch and clean, but keep getting bruising across my upper leg from the triple extension/explosive part. If this is a normal part of learning the lifts, I don't mind, but if its a sign of poor form, I'd like to fix it.
Second, I front squat ATG but when catching a clean in a full squat I have trouble exploding back up. Anything besides reactive squats, which I try to work in, to help this?
I can tell you that the bruising on your legs is most likely from the bar being too far away from your body when you bring your hips through, I had the same problem when I started O-lifting.
When I was bruising, it was because I would lose my neutral back position right after the bar would pass my knees, in turn the bar would lose contact (wouldn't be brushing along my thighs). So basically when I would bring my hips through I would hit the bar with my thighs, and that kind of impact is what caused my bruising. This also caused the rest of my pull to be way off the law of action/reaction, because the farther the away the bar is from the body, the farther out it will swing when you make contact with it.
Anyway, this is what was causing the bruising in my specific case, not sure if thats what you're doing. But to correct this you have to make sure that you are standing up with the weight (dont lift the weight off the floor, think of the weight as part of you, and you have to push it away from the floor, until you get it to the proper position to bring your hips through), and that your back stays in that neutral position until you begin your second pull, that way you can achieve a proper triple extension. And above all, if you arent doing this already, get your shoulders over the bar before you start, that can contribute to overall poor form and to the bruising. Hope that helps.