1) I'm wondering if your group DPS wouldn't shoot up if you dropped the brigand for a coercer. I don't know. I've never seen a group without an enchanter before (because my main is an enchanter, and I always build groups with enchanters). The coercer would give 96 DPSmod to your group, would give better hate to your berserker, would dehate your assassin, would make your mystic's heals much more effective, and very importantly, would give a huge DPS boost to your assassin via Enchanted Vigor.
2) I kind of disagree a little with Kannkor, as I believe casting order is very important. I think Kannkor's comment was directed more at people who have a good understanding of each class and the general ability set in EQ2. But reading and participating in these forums for a year now -- and based off my own experiences learning new classes as I went from 1 to 6 to 12 to 18 toons -- I've seen a lot of people (including myself) just not get the basics of a class. And thus their casting order is flat out "bad".
So when you look at your 6 toons, do you feel you know all 6 well? If not, your casting order is wrong. And that's ok -- much of the fun of ogre is learning new classes and perfecting new casting orders! Making a team work together is ridiculously fun. It's also instant gratification. One or two small changes can have a big impact.
3) As kannkor said, make sure you're buffing correctly. This cannot be understated. If you want, list in this thread all the buffs you're casting on other toons in your group, and tell us who they're being casted on. We might find mistakes, and one or two buff fixes makes a big difference.