There are several free programs on the web that can be used to modify sound files. I use Audacity but even the Windows supplied "Sound Recorder" has the option to increase or decrease the sound level. With Audacity I lowered the volume of the General Quarters file and shortened it a bit. That file caused a rapid increase in heart rate and sent the sleeping dogs in the man cave/control room running for cover! Man that file is loud when you are quietly sneaking up on a heavily defended convoy.
One shocking fact I found is that not everyone agrees with me or has the same priorities as me. It doesn't make any sense but there is no fighting human nature
My solution is to make my own Mod to fix the things that bother me.
As far as the map goes you can remove or change gradient.tga file in RFB. My map has a green gradient for land and the shallow water color starts at about 100 ft. Also you get the shallow water warning when the boat has about 65 ft under the keel.