For the series, my feeling is that the intro should be as short as possible, almost more for mood than for information.
The rotating narrator thing was something that I mentioned en passant at the LosCon screening of "Midnight." What I noted was that I was considering rotating the narrators each season; Londo for the pilot; Sinclair for year one; Ivanova for year two; Garibaldi for year three; G'Kar for year four; and Delenn for year five. Haven't decided yet if I'm going to do it or not....
Yes, we will definitely be changing the narration each year; the year two narration will likely be shorter, with some personal touch (I'm in the process of writing it now), and it'll vary in phraseology with each new narrator.
Second year narration will be Sheridan. Third year probably either Ivanova or Delenn. Fourth year G'Kar. Fifth year...possibly no one.
Yes, we'll definitely be redesigning the opening sequence visually as well as in the narrative.