Hellfire Citadel located in the Hellfire Peninsula will be tuned for low level 60 players so once you install the Burning Crusade you'll immediately gain access to a new winged dungeon.

opening the Dark Portal is an example of a very difficult and epic quest that would require lots of effort on the part of many Warlocks to complete

/sad panda

I'm not sure if these quotes imply no quest will be involved.

The way i forsee the transition from release WoW to BC is to have the portal opening quest begin about a month prior to expansion release and finish coinciding with the release date so that the portal "opens" the same time that players can get the expansion

There was a recent mention that the portal would be openned via some event. But yeah, it's probably not something that'll take a month to complete.

Hmm, don't suppose you have a link? I hadn't heard much about the quest lately, the pro quest quotes in the wiki are quite old, whereas the anti quest one is quite new.

I don't see it happening. I'm not sure how you square long difficult quest with the portal is open on install. The only thing I can think of is if NPC's will finish it if you don't (Please god not hand in 10 million soulshards). But if having the players finish early doesn't open the door any earlier then if your servers locks are slackers/undergeared/clueless, then its just some sort of serverwide quest to get a lock a black bug er um demon mount.