More keyboard diarrhea incoming:

Sudden Movement is At-Will Travel Devotion?

Terrifying Howl has no duration specified on the Shaken effect.

Why don't aura benefits stack with Aid Another?

I don't see why Dual Auras would require 20 levels... I suppose because it not only gives 2 Combat Auras, but 2 Commanding Auras as well. I think I would rather see these benefits divided, perhaps in the form of Advancement. Something like requiring Commanding fighter 12 or so to get 2x Combat Auras, and then it also allows 2x Commanding auras at level 18. You could also squeeze the ability to activate them 2-at-a-time into an Advancement.

Incidentally, including the ability to change Commanding Auras any time you change Combat Auras (and vice versa, of course) somewhere would be nice.

Both Expert Aid and Supporting Strike eventually increase your Aid Another bonus to +5. Was this intentional to create multiple paths?

I wish I could provide some inspiration for more Commander feats. For now, I'll suggest feats which allow you to cash in your normal Aid Another benefits for more exotic ones, but I don't know what that would be (for the most part, it'd probably end up redundant with the auras anyway).