Thanks a lot, helpful guide! =)
As for my two cents; it's possible to do disc healing as well in Karazhan. I'm doing fine at the moment, and have cleared everything but Netherspite (Though we've never tried him).
This is my spec, and I'm at the moment on about 140mp5, 1000 healing, 9K hit points and 9,5K mana. I've achieved this mainly trough grabbing the Season 2 arena set and gemming it with any kind of +mp5 I could find. I use the
Serpentcrest Life-staff which drops off the second boss in the steamvaults and a
cloak which is obtainable from the first boss in the place. Furthermore I wear a pair of
badge bracers and picked up the mighty fine
Light-Woven Slippers from the first boss in the Sethekk Halls.
I've since then replaced the leftover slots (necklace, belt and a ring) with Karazhan gear, though make-do items can be found mostly off the quests that lead into Coilfang and Auchindoun. All of this gear is fairly easy to obtain by just doing a bunch of PvP and running a couple of instances. Completing the whole set took me about a month (I retrieved some of the instance gear while still levelling), though with some effort you could probably do it in two weeks and have the choice between PvE or instances at hand.