I have done informal experiments that convince me that at least some fish respond to ones bubbles. On a trip to Oz where there are many small fish in coral heads it was very obvious that they would withdraw as I approached. Upon stopping I noticed they would go in and out of the coral heads according to my breathing. I purposefully modified my breathing pattern and they changed their in and out pattern accordingly. I have seen UW footage where the fish were exhibiting a similar behavior. I could 'visualize' the breathing of the cameraman by watching the fish in the footage, which followed a normal breathing pattern.
I suspect just moving the exhaust to behind the head will be beneficial, especially with a 100mm and longer lens (still photography). The extension hose would probably be better - is this an old trick from the 1960's when 2-hose regs were popular?