hi ! in generally prepuce(inner skin) is some what sensitive to touch as it has very fine nerve endings, but in few men sensitivity is more, due to increased nerve supply, if it is very much trouble some, you can go for circumcision, this solves your trouble. coming in to size, size of the organ is never a matter medically or scientifically, its just a misconception drawn from magazines and all. in general a nrml erect penis measures about 41/2inches - 6inches which is nrml and absolutely natural.