They changed the Talent system such that it forces you to specialise in one Talent Tree before opening up the others. And compared to the previous 2 expansions, the Talent Tree has also been trimmed back to 31 points (vs 51 points in WotLK)

By the way, I distinctly remember a way to filter out the thrash on /Trade. Was it a mod? Or was it the ol' /ignore?

Don't mean to sound like a gosu, but that's just complete bull. DPS roles need to do more DPS than tanks, and tanks compensate with their respective threat skills.

The times when you see a tank outpace the DPS in their own field are usually when the tank knows his/her rotation inside-out and/or has much better gear than the DPS.

Another point to consider about normal dungeons is that tanks are usually attacking multiple enemies, whereas most DPS are single-target, hence the seemingly lower DPS. Try resetting Recount (or similar addon) before a boss fight. If the tank is still outpacing you, then I seriously suggest reading some guides on your talent spec.

Depends on where you left off, but the stat system has been simplified and changed a great deal.

Few months implies WotLK, which means you should be aware that Paladins have changed a lot since Cataclysm. As for Ret's "nerf" it'll depend on your reference point. Compared to 3.0.1, yes, Ret has been nerfed bad, as needed. Right now, I feel Ret is fine, although I still prefer Solo/World PVP as Prot any day.

If the launcher is in Stage 2 of 3, then you can still log on and play while the update downloads in the background.

No point paying for the transfer if your only character is level 20. With the current rate of leveling, that's about 8-10 hours of game time.