And does dex, and wisdom help spell casting?
I am just very new to magic in Nwn. I am more specialized in great sword paladins who are immune to scare and etc spells.
Funny you should mention pally because it is the natural synergy class for sorc. A single level of paladin
will vastly improve your saves and allow your toon to equip martial weapons. 2 levels will make you immune to fear which you are already aware.
However, assuming you can reach the maximum level 18 in the OC it would prevent access to level 9 spells which require at least 18 levels of sorc. But using a henchman, summon and familiar in encounters will reduce your combat experience drastically, somewhere around 10-12% per ally, so the prospect of reaching level 18 is a dubious expectation at best.
WIS is used for Will saves which a sorc already has as its high save. Not needed much. Use empowered Owl's Wisdom,
if needed for an extra boost vs. mind effects like fear.
CON is used for Fort saves,one of the typical weaknesses for mages, and HP total. Probably #2 priority just behind CHA.
DEX is used for reflex saves and AC but it (the AC) can be lost under certain circumstances. There are defensive feats like Dodge that require more DEX than is customary for a mage to allocate. Some mages like a bit of DEX to make their xbow better. Buffing with empowered Cat's Grace will raise the AB up to +3 in those cases.
INT will boost your Spellcraft, being able to recognize enemy spells and increase skill total.
STR is about worthless for a mage unless playing a spellsword of some kind. Most will use a polymorph like Tenser to melee, if needed. Empowered Bull's Strength can raise STR up to +7 when you need that extra boost.
CHA you already know about, the #1 priority for sorc.
As a player new to the game, check the NWNWiki
(if you haven't already) to help you learn the basics, the advanced concepts and everything in between.