I have a question for Dexter afficianadoes.

Are they showing the CBS versions in the exact same order as Showtime? Because so far they have only shown two episodes, but sometimes it feels like we've 'walked in' on a season already in progress. I don't mind that, actually. It's clever if that is what they have done.
Also, do they ever delve more in to Dexter's background? They've briefly touched on the desire to kill when he was younger, and how his foster dad noticed it and channeled it toward the bad guys. But so far they haven't really explained why that one guy hates him so much (forgot his name, bald black guy) and why his Lt. is so infatuated with him. Just wondering if these things come up more as the series progresses, or if they just leave them out there and we are to make of them what we will. Plus, I'm curious if there is ever any explanation regarding his desire to kill.
Thanks.