1. Id say you wont see many people leveling alts now, i have 5 at 90 and want to level a Cloth/Enc but its so fast to level now with hierlooms you whizz through the levels in no time. PVP is generally done in Battle Grounds and Rated BG's cause the whole content is so vast now i think your be hard pressed to find anybody to PVP with in the outside world
2. I am sure your still be able to do them as you can now que in the Dungeon Finder
3. Pretty much as i said above, level so fast you dont get a chance plus all the worlds change in cata with all new quest lines and areas revamped
4. I dont know the answer to that, i vaguly remember you cant continue to level but its not a problem really cause it takes 5 mins to level to 20 ???
5. Talents got removed to stop single talent trees, most talents now are just a side talen of all the others.... Which i sort of like and sort of dont.
6. Dont think shes missed the boat but the game has changed, i am enjoying Pandaland Content still 6-8 months in if that helps and been playing the game since 2006 i think ? i never did the old original game and Dinged 60 1 week before TBC ?
Hope that helps, get yourself to 90 ASAP and explore Pandaland