For the pedophilia...well I guess Japs like the idea of teenage intimacy. Almost all the animes revolve around teenage/young characters. Since it's anime they can draw them however they like and make them do whatever they like. Since anime viewers contain a majority of youth audiences, the makers probably think we'd like to see younger characters. Every once in a while in school you think "Damn, that girl's fine". Well, as a substitute you can think about some anime girl instead, and thus hentai was born...ok enough of that.

Gundam Seed was the first series I've seen that's really gotten into it. The intro itself (you know those scenes) would get an adult rating over here in North America. I think it's a marketing strategy or something to use young characters with extensively developed bodies.

It seems that the Japanese populace isn't as strict about what's "appropriate" and what's not for younger audiences. Levels of violence/language is uncomparible to western shows. Over here, anything with a G or Y rating isn't allowed any blood/gore, while the average anime watched by a lot of kids has blood & gore all the time. Think back to the beginning of Naruto where he stabbed his own hand. That would never make it to North America.