Baby steps...

[Bollwerk]

A couple things -

41-something defense? That seems wierd. You need 535 Defense (to be uncrittable) for heroic bosses (540 for raid bosses). You said she survives fine, so I'm not sure what the deal is there. My pally only has like 33k health, but I rarely have to heal in heroics, which is one reason I love having elemental shamans. I can heal once in while, without suffering a loss of dps.

You mentioned some aggro issues, especially with the mage. I would recommend making sure you have the mage specced with 2/2 Arcane Subtlety. If you are already specced with that, then maybe you need to tweak your spell rotation with the pally. Personally, I have up Seal of Vengeance (and BoSanc / Righteous Fury of course) and cast a 9/6/9/6/9 rotation to keep AE aggro. I use Consecration / Shield of Rightousness / Holy Shield / Hammer of the Righteous / Judgement of Wisdom on a /castsequence reset=combat - Also, you may want to gain threat for a couple seconds with the tank before opening up dps.

I don't have any mana issues during fights, but I do often need to drink between battles. Between Jundgement of Wisdom / Blessing of Sanctuary and occasionally healing your tank, you should generate plenty of mana during fights, as long as you keep all mobs in front of you. (since BoSanc relies on dodge/parry/block to generate mana and you can't do that to mobs behind you)

As for respecing / dual specing the mage, I have my mage as Arcane spec now (with Fire as 2nd spec) and I'm finding that I really like the DPS output of Arcane. I use a simple macro of /castsequence reset=combat 3x Arcane Blast, Arcane Barrage - that's it - I don't bother with the missile barrage proc unless I'm playing her solo in a raid.