I've got a couple of questions and I don't have my books handy.

We all know that Mystic Adepts can get both mage skills & abilities along with Adept powers.

Can Mystic Adepts get Improved Ability (Spellcasting) just like they can with Firearms, Blades, etc? If so, the cost would be 0.5 / Dice, correct?

What would be the limit on the rating of the adept ability? I know that you cannot have more dice from this than you have in the skill. But there are other limits that come into play such as Magic. If I have Magic split in a 3/2 manner for Mage/Adept purposes, what is the maximum rating I can have for adept power ratings?

No, they can't so any planing based on this is useless. Magic skills are not affected by the Improved Ability. Combat, Physical, Social, Technical, and Vehicle skills are.