Oh yeah! Big Babylon 5 fan here too!
I was in my late 20s when B5 came on and I kind of consider it to be the Star Trek of my generation. It truly was groundbreaking in many ways, just like the original Star Trek was. I was a bit too young to see TOS Trek when it was broadcasted on NBC, but fell in love with it later in the very early 70s when I was 5 or 6 years old. It was great to see a show as amazing as B5 or Trek first hand when I was old enough to appreciate it. B5 is now the measure I use for all other sci fi. For example, I really like Stargate and Farscape, but they're no Babylon 5. 
As to Moby Dick, yes, Norman Spinrad who wrote that episode has said publicly he wanted to write a Moby Dick/Ahab-esqe story in a future setting. When invited to write for the show, all he was told was, to save money, he had to keep the action on the Enterprise set so they didn't have to create a set for a new planet or environment. Keeping it in house and with only a single guest star helped keep the budget down.
Another budget saving move was to not use Spinrad's original design for the Planet Killer. They simply took a aviation wind sock and dunked it in cement!
I wrote to Mr. Spinrad, hoping he had a drawing or something of the original design, but he was not up for that. The only think I remember is was supposed to be "bristling with evil looking weapons". Let us always remember folks, Star Trek; The classic, the Original, the One and Only!
