Sometimes it does this even if you don't do anything after rolling to the side, just flip it over, don't touch the controls and it'll magically right itself.

Something tells me smokes shouldn't work underwater at all. IIRC, they generally contain a chemical compound that creates the smoke, not compressed gas. I don't think this reaction would occur at all in the water, or at least not the same way as it does on land.

Up-voted. I think that ideally, this would be paired with making cocking the weapon a separate action, so that there's no problem when you want to reload a different kind of ammo.
Also, a different, faster animation should be substituted if you've got no rounds left in the mag. At least with an M-16-style mag release, you may push the mag release with your trigger finger while reaching for a new mag with your other hand. If you're discarding the mag, this makes things faster.

I think it needs some adjustments, but nothing dramatic. I've fired a RL AK-47 (while standing) and had somewhat similar accuracy, on the other hand, I'm not a solider and ArmA III doesn't have AKs.

Ideally, there should be multiple NVG types, including a version for divers. Normal NVGs don't stick to your face like diving googles do and even if they'd work underwater, you won't be able to see a thing.