When coppicing hazel - do you normally cut all the old growth down to the stump or just the bigger stems?
I think you need some books Smojo, they'll answer many of your questions. Just taking occasional big stems and leaving the rest is I believe called 'draw coppicing'. You will get some regrowth, but not as vigorous as when you cut the lot to the ground. Another key factor is light, to maximise regrowth you need to maximise light, so decents sized areas or 'cants' are usually cleared, so the shoots aren't shaded. I sometimes leave 2 or 3 smaller whips just so part of the tree is generating food for the roots, but clear 90% of it. Clearing a large area also gives a surge in wild flowers, insects and birds, which is one of the features and potential attractions of the coppicing system.
Books. They are useful. (Titles as previously mentioned).