Is this dead then?

Also, something I've noticed, and I don't know if I missed it or if it's not there, is that there is nothing in here that let's your attacks (tentacles, razor fins, mouths, claws, etc.) count as magic for the purposes of bypassing DR. Was that intentional?

Might want to have them count as enhanced since even if the class had a full BAB if it doesn't have those bonuses to hit by a magic item, it's taking a serious hit to attack rolls (I mean I know it gets a lot of attacks but still).

I'd suggest having count as just a straight enchantment (+1, +2, etc) or have it be an augment for your attacks ie you have to invest form points in each attack that you want enhanced or maybe just in each attack type (tentacles, mouths, claws, etc.).

Maybe have an augment that let's their natural attacks count as certain materials for the purpose of bypassing DR (or maybe just have it converted to those materials though that might be pushing it).

Another augment that could be added to the mouth could be acid (like acidic saliva) with the justification that it helps break down the food and make it easier to digest.

Or they could spit acid as a form of ranged attack (I mean reach is very nice but there are still times when you'll need to shoot something out of the air) as augment for mouths. Have it have a duration like Melphs Acid Arrow spell.