1. For your 1st question I'm going to quote what I found in the official forum.
Solo:
Int Build - 2 to 3 Int. 1 to 2 Vit
Wis Build - 2 to 3 Wis. 1 to 2 Vit
Whichever build you choose, you will still want to get 50 Int or 50 Wis.
Party:
Int Build - approx 3 Int. 0 to 1 Vit
Wis Build - approx 3 Wis. 0 to 1 Vit
Just like Solo, you'll still want to get 50 Int or 50 Wis no matter which you choose.
Int build goes Warlock.
Wis build goes Wizard.
It is possible to make your character an Int build, and then when you're ready to do the job change reset the stats if you're going for Wizard.
2. I'm not exactly sure if I understood what you asked so sorry if I don't give you the answer you were looking for. All races do the tutorial mode in the same zone, after the tutorial each race will be teleported for a new zone. Dark Elves are teleported to "Ignis".
3. I played a DE in CB but honestly I don't remember about this one but I'd say you still deal magic attack (but not that damaging). Skills don't consume much mana so you can sorta abuse on skills, besides there's a skill that restores your mana.