Chrisarah81 - The only episodes I'd suggest you avoid are Tweek vs Craig and The Passion of the Jew. South Park has its fair share of average episodes, but those are the only two REALLY awful ones. As for things you SHOULD see, definitely try to get your hands on Seasons 6, 7 and 8. They're easily the best seasons of the show (particularly Season 6 - not a bad episode in the bunch).
1. Comedy Central didn't censor it. Yes, they refused to air the image of Muhammed, but the South Park staff knew weeks in advance (hence all the jokes about networks "pussing out"). The censored screen that appears when Mohammed enters the room was done by the South Park staff, not Comedy Central.
2. That clip is fake - I mean, just look at it. Firstly, Mohammed is in South Park style rather than Family Guy style. Secondly, his lips don't move when he talks, and the sound byte is from Team America. Thirdly, the edges of Mohammed are blurred, and overlap the lines of Family Guy. Forth, only his eyes move when he looks down - a true South Park character would have their head rotate a little, too. And finally, the clip has a Comedy Central watermark on it! How did that get there when the footage never aired?! It's fake, one of SP's producers even said so in a recent interview. I can't believe people are still getting duped by it...
Anyway, onto the new episode, now. I'm not quite sure what to make of A Million Little Fibers. On one hand, I normally like South Park's mindless, over-the-top stupid episodes (eg. Prehistoric Ice Man, Towelie, The New Terrance & Phillip Movie Trailer), but this one was pretty crappy. Towelie had a few good lines, but aside from that, he was the only real South Park character in there. The episode really fell apart when Oprah's "minge" and "Gary" came into the story... I'd say about 20% of the entire thing was just a close-up on Oprah's pants, and that's just plain poor show-making. An episode idea that had a lot of potential for humour, but lost it all in the execution.