Wizard stat points

[Nite]

Does the Attack power stat also improves Wizard's damage or should i focus on Intelligence ?
Is it worth to stat also for Vitality or Vigor for this class ?

Also, I found some skill books that have ranks, but cannot be upgraded with gold... how to improve these ?

[LaroqSoqs]

The Ancient Books are Stacked up to ten, so you find more to improve the rank.

Sorry I've only just started a Wizard character myself, but both Intellegence and Attack Power stats improve damage. On the wiki it states Attack Power gives 4% increase to damage, and Intelligence gives you 2% increase in damage and one additional shot.

Elemental Damage (Magic, Fire, Lightning, Poison) is buffed with crystals and armor etc, which can help make up for that 2% difference if you decide to focus on Intelligence.

When it comes to Vitality, I always felt 50 additional points per level is too low, so I avoid spending any points on it and use Crystal and Armor buffs to increase HP, that way I have more points for the other stats as well.

[Nate]

I’m an enchanter but I went attack+int, mostly attack, never put a single point in vit or vig, I used my buffs/crystals to still get 100% resistance from vig and an ok amount of hp+mana for wand attacks

[Duck]

Attack Power = all damage is increased (4% per point)
Int/Dex = Wand/Melee Weapon damage is increased (2% per point)

Attack power, as indicated above, will increase skill damage as well as weapon damage, where as int/dex will only raise the damage of skills that get a weapon bonus. If you're looking to raise most skill damage, it would seem attack power is often the best choice (even over elemental damage boosts from my previous testing). If you have a weapon damage component then you should test out the numbers to see what works best for you. Ultimately, just test out the numbers with some different gems of choice, just in case I'm mistaken.