On Genre
House - Jazz, Funk, Hip-Hop samples used and usually a trip-up / swing beat (boom shh ka sh
kaboom shh ka shh boom...)
Trance - Very strait forward 4/4 beat structure (boom shh kaa shh boom shh kaa shh..) Very effects based melodies.
Techo - I find Techno to be the "everything-else" category. Still 4/4, but the emphasis in my opinion is based more on what cool sounds you can use to fill up the beat. Very few techno tracks have a "melody" and their loops tend to last a little longer. Certainly not for everyone.
Dubstep - I think this is technically a 2/4 beat where the drums are half the tempo of everything else. There's also the "dubstep-wobble" that is used in the bass which sounds like a "WOW"
Hope this helps. More to come if needed.
