my first suggestion would be read the manual if uve read it read it again. now that uve played a little bit of the game some of the manual will fit in better. As for the quests you are given, quests do not have to be completed straight away the spider quest is not super important.
The amount of spells you can have in your mage book depends on your mages intelligence ... i think... either that or wisdom (once again the manual will help with this). If your mage has a low intelligence stat then he/she cannot learn as many spells.
For fighting, my favorite tactic is the use of the space bar is pauses the game and allows you to have more control in the battles. Setting one command and watching the battle unfold is fun to watch but it wont win a whole heap of fights especially early on in the game. so pause the action every so often and rethink your battle stratergy
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Nor shadow or myst
the jester is a myth
he is absolute
beware the jester