Get to 80 first.
Run Randoms and get T9 with your tank and healer.
Run randoms yourself till your whole group is geared.
Worry about the rest later.

There is nothing wrong with caster gear on your tank as long as you meet the required goals for tanking. High hp and def cap. I run with 2 pieces of caster gear on sbjones except when raiding. 10k mana over 5k means that all my mana regens are double what the were so I dont ever have to stop and drink. w/o the caster gear, im so overgeared that im oom after every other pull or sooner. Things die to fast to get any reasonable mp back from sanctuary and divine plea was not enough and I dont take any damage being block capped to get mana from heals.