The Beluga has been mentioned before, a much larger passenger vessel that's a custom job. The Narwhale is evidently, from that GalNet piece, a more highly customized version of the Beluga, probably more weapons, more armor, more defensive measures, faster top speed, jump range, etc, as would befit something being used by the head of one of the largest galactic powers in the Human sphere of influence. Much as Airforce One that the US President uses ISN'T just a hopped up 747.
As to passenger missions and carrying them around...sorry, but you guys are NUTS to want to do that stuff, listening to whiny passengers, dirty diapers being left in the seatback compartments, all that other nasty stuff that goes with carrying people around like that...ugh! Star Citizen is going to do that all up, supposedly, and when I was reading their proposed gameplay for it I was like, 'are you g kidding me? Who the hell would find that fun?'.
Then I realized, I love being a thousand light years out in the Black, scanning yet another lifeless ball of ice or rock, and I'll do that for months on end, so really, who the hell am I to say something is or isn't fun for anyone else? If people enjoy it, more power to them, and by the gods, lets hope FD and CIG get it right for both games, because come on, the folks who love doing that stuff really ain't got much choice in other games for it, just some flight sims, and lets face it, it's a lot more of a thrill to think, 'if that stupid mother's son in F3 doesn't shut up, I'm gonna space his ass!' then to think, 'if that stupid mother's son in F3 doesn't shut up, I'll have a massive headache when we land'.
