Honestly I didn't bother reading the other walls of text, so this may be repetative:

-Get used to playing with the tactical camera. Early and mid-game it is necessary for proper positioning your party and to set up combos.

-Identify your clutch abilities and remove them from the AI tactics. Things like an Archer's upgraded Full Draw (20 second single target sleep, refreshable; cooldown is less than duration) and any Mage's Barrier are abilities you do NOT want to see on cooldown when you really need them.

-Consider getting the extra potion slot and maybe even upgrading the maximum number of potions you can carry. Equipping all your characters with Regeneration pots will help you recover out of combat and save your insta-heal pots for in-combat scenarios. The third slot can be used to equip a variety of tactical grenades. Slow Pitch is excellent for keep enemies grouped up for combos and aoes, and the Jar of Bees does more damage than it has a right to, being a damn Jar of Bees.

-Most encounters have a 'key'. It may be one particular enemy that needs to either die fast, or be crowd controlled throughout the fight. The 'key' might be as simple as a bottleneck near the engagement area or a pillar to line-of-sight ranged attackers, making them come to you rather than having your party cross an open arena to engage them.

-It's okay to not play as your Inquisitor; different encounters play to the strengths of different classes. Some have good terrain for archers to get above the action, and you'll benefit by positioning them and protecting them while they dish out the extra damage. Other times, you'll want to control bottlenecks or specific enemies with your tank. As the player, you'll always be better than the AI so, if the situation calls for it, take control of those lynch-pin party members to make sure things are done right.

Hope it helps,
Solkahn