A couple of turn questions

I have a couple of turn-related questions: 1. When you do turns for *** strokes/flies, I understand that you must place both hands on the wall simultaneously. As long as you do that, can you grab on to the edge of the wall with one had so as to pull your lower body towards the wall, or are you only allowed to "touch" the wall with your palms but not to grab? 2. I have the "Go Swim All Strokes with Sandeno and Vendt" dvd. Both of these olympians employ what I would call "side" turns for back to breask transition in IM. Aren't you also allowed to roll over onto your bellyside and do a tumble turn? Intuitively, rolling over and doing a tumble turn would be quicker, but neither Sandeno nor Vendt does that. 3. Again, in that dvd, neither Sandeno nor Vendt appears to stay underwater quite as long (they only did two dolphin kicks before surfacing) after the ***-to-free turn as they did after the fly-to-back turn or back-to-*** turn. Is there any reason to break water sooner after the ***-to-free turn? Thank you in advance.