There is no need to have people re-level like in gw1 campaigns and of course you'd want most new zones to be lvl80 but a few low level zones added would keep balance.
Exactly. With scaling, it doesn't matter the level of the zones.
Also, Lonami - you should be a Game Designer as your ideas are awesome
And yeah, the zones of those ranges need cool metaevents so people has fun. Those zones aren't as polished as the 1-25 and 70-80 zones.
Now, the biggest feature for a GW2 expansion would be a huge Codex, for the Lore nuts like myself, since while there is a lot of Lore ingame, it is presented poorly, IMHO. WIth the Codex, once informations have been unlocked, you don't have to go through the deepest end of a zone to read it again.
Still, you're work is awesome, Mister Lonami.
Edit : just read the whole thread (Old and New), and it is even more awesome than I though. I especially like the Watchers, the Region Ranks and the Dungeons... even if I would have added one to unshroud the mysteries around the Ogres, Kodans, Norns and Jotuns, all specis which seemed to be tied to one another (at least, it is the impression I got after reading the old Arena.Net blog's posts about them).
I think the story is fine. Storytelling, however, is very bad in this game. Just go and ask people about memorable characters or storylines, there's pretty much none. The game is awful at storytelling, and if I had the power to fix anything, I would fix this before anything else.