I'd say get all magic schools up to at least 2. There are several great early access spells from all schools and as you will be focusing on intelligence you gain the most from them.
Your specialization would come in choosing which schools you wanna bring up to 4 or 5.
Far Out Man is the best starter talent for mages, no doubt. Pet pal gives you access to a bunch of extra quests and may also have clues to help you figure puzzles out. Other than that I'm not terribly impressed by the starter talents.
Glass Cannon is extremely strong in easy and normal mode. It's still good in hard mode but you will really feel squishy until you get your Constitution up. This talent will make the game a bit too easy according to many. You have been warned.
If you are planning on bringing companions I would make Jahan your crafter as he starts with Scientist talent.
As you progress you will be able to trade 1 talent point for 10 ability points and 10 ability points for 2 attribute Points. That means that talents that increase your attribute or ability points are worthless.
Having at least one summon spell per mage is great, especially early on.
Attribute wise you should focus on increasing intelligence, but it's also well worth it to get speed/con up to 7 through gear.
Here's list containing all skills, including spells:
http://divinity.gamepedia.com/Skills
