I have no clue where the full contact kumite idea comes from but in my experience most kumite is not done full contact. Pads may or may not be used depending on your clubs policy (ours uses hand and shin pads). Off the top of my head rules are generally - no hand or elbow strikes to the head/neck, no joint attacks, sweeps are ok but throws are not, no strikes to the back, no strikes to downed opponents.