1. Gearing up wise you got a fair few choice. Make sure your doing Hunts as they can give you seals for iLV170/180.
Dungeons offer of course tomes and some gear as well. Midas gives you 220 and WC gives you 230. So there is quite a few ways and of course tomes.
also right side, vit gear all the way. VIT and STR both offer 0.45 in terms of AP but with VIT they have a few more points over STR when compared of the same iLV.
Also you can meld STR on VIT gear as well.

2. your bonus points should all be on VIT. VIT and STR effect your AP now *yes vit counts towards the amount of damage you do now* but given that vit offers HP as well all VIT. Piety never stack anything on that for DRK.

3. CD's it depends on the fight but general if your doing big dungeon pulls don't pop all your Def CD's at once.
I tend to pop shadow Skin and foresight then when they wear off shadow wall and then once that wears off but by then most mobs should be dead conv and dark dance.