Really interesting-looking species! I've also created a race of four-armed creatures and I went through quite a lot of designs before I found the kind of anatomy I was happy with. I made the lower pair of arms smaller in size (seemingly weaker, too) and positioned them closer to the chest, sort of attached to a secondary set of collar bones.

Uh, I always get carried away when it comes to these things.

The colourful leathery... um, what should I call that thing? ...thingy around his neck reminds me of this one dinosaur species. I wish I could remember their name. Anyway, it looks pretty cool. =)

Crest, it's a crest.
I thought about the arms being smaller, but in the end they actually worked being roughly the same size, they don't rise as high as the upper set does, but they have a longer reach because of their possitioning.