In keeping with those ideals, a five year storyline (the "arc") has been planned as if the show were a five year miniseries. Events have been planned for each season, which will tell a larger story over time. There is plenty of room for individual stories within each season and each episode can stand alone, though certain episodes (which JMS calls "WHAM" episodes) are pivotal to the big picture -- for example, "Signs and Portents" from season one.
One common complaint about science-fiction shows (and TV in general) is that fan input falls on deaf ears. Not so Babylon 5. JMS participates in online discussions in several places, such as CompuServe, GEnie, and Usenet, actively soliciting discussions and thoughtful criticism about the episodes and the show in general. Some of this online discussion even goes onto a "Best of the Nets" bulletin board on a wall in the production offices, where it's read by many of the staff.
In fact, since the airing of the pilot, fan input has had visible effects on the show.
All freelance scripts have the original writer as the sole credit. Contrary to prevailing practice in Hollywood, any rewrites or additions (such as a "B" plot or additional scenes) by Babylon 5 staff do not add to the writing credit. This allows freelancers to get full royalties for the episodes they write.