Things like K9 Units and pepper spray were thought to be impossible but Hoppah and the NY Mod team have done them. Tillers were thought to be not possible to do nd they have been done. I'm sure someone could do this if they tried.
I only use the K9 for calls when the criminal is armed. I think the drop a diver button is the same as the dive command on the diver. It won't drop if the helicopter isn't over water either (I tried ).
They don't run out of water in the original game either. Hoppah hasn't made a script for them to run out of water. BTW Don't double post. Use the edit button.