Like the content within the most recent 4.0.3 patch (i.e., the shattering), all the changes and new quests, etc. are available to anyone with the base game.
According to the official patch notes: http://us.battle.net/wow/en/blog/1214741
The new race / class combinations are already available in the game. (See the 2nd bulletpoint, reprinted below):
New Race/Class Combinations In the
wake of a world on the brink of
destruction, members of the Horde and
Alliance have taken to new cultures
and studies, mastering crafts
previously foreign to them. Many
existing playable races now have new
class combinations. Check the official
World of Warcraft: Cataclysm website
for a breakdown of the new
combinations.
Reading this as 'how do i evaluate my damage', weapon dps ratings don't really matter, nor does what the weapon hits for individually. Its what you do in a particular fight consistently.
For this you need some sort of a damage meter such as recap or skada, or if you really care to get into it worldoflogs client.
Another issue is that if you are stunlocking, kicking or otherwise supporting a group, that should be noted and those fights removed from your trends.
So if you are doing Sm Armory in a group, and on all the trash elites you are pulling 120dps, with 98% attendance, 12% miss rate, etc. I would say thats pretty good, likely your getting a buff or two from your group as well. That's what I would expect from a one button single target macro mage.
If your significantly lower than that, I would suspect your rotation priority are to blame, also new rogues have a problem baning their combo points for killing blows that get stolen by other characters in a group, or they don't know how to deal with large health pools on mobs so the build up combo points and then unload damage, forgetting things like slice and dice, bleed, and so forth.
If you suspect you are leaving combo points on dead mobs, there are addons to tell you that. If you consistently have 4 or 5 combo points left on a mob, you need to revisit your style.
Best Answer
The Forsaken quest line is something special!
I would advise you to check out Eastern Plaguelands, level 40-45. The Caravan quest chain is quite fantastic. It starts near the bridge between the Western and Eastern Plaguelands.
As a second choice consider Thousand Needles, level 40-45. You'll be collecting ingredients to resurrect a pirate troll and reunite him with his wife. It ends with you confronting Magatha the hag, who poisoned Garrosh' weapon in his duel with Cairne Bloodhoof. To top it off, Thousand Needles is a beautiful zone.