Re: Forward Roll: tap the mat or not?
You should do it, it'll help later on with more difficult falls. There's a question of developing your sense of timing in there somewhere.
Frequently you may be asked to do things slightly differently to how you normally do them or how you like to do them, or how they "naturally" work for you. It's all part of learning to control your body fully. You should tap the mat, but you should equally well be capable of not touching the ground when you decide it's a bad idea.
(At the same time, don't go hitting the ground with your arm, let it slap down naturally- but only when you decide it should.)
I frequently end up training with people at courses who're doing a rather different technique to that which was demonstrated because they know "their" way works for them. They don't appear to realise they're trapping themselves in that one version of that technique, and will happily dismiss the potential lessons of an experienced teacher. I don't understand their attitude. But I'm rambling...