I've also been wondering if the stuff in the intro happens or not. While I don't things happen exactly as shown, I feel that the general tone and matching of characters will fit with the intro.
Ex: Kenpachi attacking Ichigo on Penitence Tower stairs in opening, didn't occur there, but they did fight it out.
Ishida vs Hitsugaya in a river, probably also a fight coming up, but location may differ and Inoue may be involved.
Chad vs. Capt ? & Yorouichi rescuing him by breaking his sword. I feel that Yorouichi coming to Ichigo's rescue was intended by this scene, but they just didnt want to show it as it would give too much away and used Chad instead. Besides, Chad is in jail/ sick bay and who knows who he'll have to fight to escape there...

Yorouichi and Urahara are probably very respected Shinigamis from way way back. I believe they were either exiled from Soul Society or died there and then were reincarnated in the Living World.