First of all, I'm sorry if this has been discussed elsewhere, but I couldn't find any related topics using the search function (search words being "too common") and taking a look through the pages.
What's been bothering me most about vanilla WoW, is how the game moved at a pace I simply couldn't keep up with. I took my time leveling and experiencing the game and did both PvE and PvP. TBC started and I had only seen MC, ZG and didn't manage to get even the first PvP set.
At what rate does the content get unlocked (I read the FAQ, but it also states that it's depending on thow fast the players clear it)? I'm already at a late start, so will I have to worry about people already having moved on? Will I finding groups to clear the 50+ dungeons? Will there still be people left in the "starting" raids after the various follow ups have been unlocked (I don't even kow what the newest raid is here)?