Post by Dunsinane
On the whole, it sounds like you have a good grasp on what you need to be doing. What I'm going to be talking about here is for level 70, and I'm assuming you're planning on building up to heroics and raiding.
Spell hit (to the cap) > Spell damage >> Spell Crit
Spell hit will be hard to find at first, so don't worry about it too mcuh. Do some research (or just crib from my list in this thread: http://www.wowhead.com/?forums&topic=17594&p=155042
) and build your spell damage consistently.
Full details on spell hit here: http://www.wowwiki.com/Formulas:Spell_hit_chance
For a new 70, spell haste won't be worth much. It is far less valuable than the other three stats until you can accumulate a LOT of it. Spell penetration is basically a no-go in PvE, as there are very few mobs that have specific resistances to break through. Stacking Mp5 would require us to take away your union card - with dark pact and life tap, you have plenty of mana recovery.
Gem selections are good. Runed Living Ruby, Veiled Noble Topaz, Great Dawnstone.
Don't worry about Int enchants. Spell damage, stamina (where you can't get damage), spell hit (if you need it), and stats for the chest piece.