1. whether or not it decreases stimulation during intercourse cannot be proven. You would have to poll people pre-circumcision THEN post-circumcision to compare the difference. Since, this can't be done no conclusive result can be attained.
2. Studies have shown that circumcision can reduce infectious disease. However, this usually only applies to the third world.
3. Female circumcision is a barbaric activity usually performed on fully conscious teen girls with anything from a knife, to glass, to even a sharp rock. It usually ends in mutilation and disfigurement. (so help me God do not say male circumcision is mutilation or disfigurement, I can send you photos of what happens during female circumcision if it will make you see the difference and shut you up)
4. Circumcision is typically based upon religious or cultural tradition, if it is done by a medical professional (or trained Mohel) and the parents both agree to it, I see no problem with it.