Without spending a great deal of time resurrecting and re-killing opponents, it would be hard to get above level 53. The most common end range for the game is mid forties to low fifties.
Wisdom - is it worth the skill points?You get one skill point per level, with IIRC a bonus point every level evenly divisible by 5. Between quest rewards and spell books, you could get another 50 or 60 skill levels by the end of the game.
Free skills, and spell books you can buyThere are no robes, but the merchant in the elven village in the Dark Forest sometimes has mithril armour (also available as a random drop), which is quite strong without the high strength requirements. There is also a special breastplate in the Dark Forest that is invisible on your character, sometimes preferred by mages that don't want to look like they are wearing heavy armour.
differences between classes (minor spoilers)
Early Starter Tips (NON-Spoiler Version) (contains much of the information in the above topic)
I don't recall any weapons that require intelligence in DD (there are in Beyond Divinity).
Kaan's Mage GuidePlaying a mage character...
