With weapons, any magic damage gets a boost from intelligence, while conventional damage gets a boost from strength. You can ignore strength, if you wish (though it does help your healing rate a bit), and focus on magic or balanced weapons.
In D2:ED you could not put damage enchantments on jewelry. I think in DKS they apply to weapons and spells.
For skills, from what I've read, you should go with Magic Missile and either Fireball or Magic Blast (probably don't need both) for combat, Firewall for close quarters fighting, plus Destruction and Mana Efficiency.
You can take a look at the D2:ED topic
The official "ULTIMATE MAGE" guide, but some things have changed in DKS (especially the magic damage weapon enchantments being applied to spells).
