1. Ive heard he got it fighting someone named Assajj Ventress, a dark jedi or sith or somthing. Maybe i'm wrong though, i'm not a huge EU fan.
2. They are called jedi interceptors, also known as Eta-2 Actis Interceptors I believe.
3. I don't think there is a reason really, just the way the uniform evolved. The Empire probably didn't really care enough about individual troopers to give them camo armor, they're expendable in the Empires eyes.
Not being paranoid doesn't mean someone isn't trying to kill you... or does it?