1.) Techno is a broad genre in which many other sub-genres fit into (just like there is Rock and Roll and sub genres of Rock and Roll include Indie Rock, Metal, etc.). Big Beat is like Chemical Brothers, the Prodigy, etc. Trip-Hop uses hip-hop style beats with usually slow tempos, dark vocals and "scratching". Examples of trip hop would be Portishead, Morcheeba and Massive Attack.
2.) I'll tell you when you are old enough to have sex.

But I wouldn't need to sleep with Laetitia Casta to tell you if she was sexy or not.