As to your question, I think you have to have behaved inappropriately with an actual child to be labeled a pedophile according to law.
I could be wrong though...maybe I'm thinking about being labeled a molestor rather than a pedophile.
That said, child porn would put one high on the suspicion list of tendency toward pedophilia AND molestation. Suppose some child is molested but they don't know the perp. The cops would take a look both at known molestors and at child porn involvement when looking for a break in such a case.
Clinically put, a pedophile is an adult person who desires sex with children.
http://www.lege.cz/archiv/pedo1.htm