Tomik18 These are really scripting questions. But to answer them quickly, background
music can be switched with the command "musicoverride=x" For no music/sound and give it a "blank" sound file
to play. For a door with no sound just remove the sound files from the doors "property settings"
And to remove "footfall" sound, try these...
Add to an entities .fpe file.
nofootfall=x
For the player use a trigger script
plrfootfall=x (1 on, 0=off)
I haven't used these in awhile, so let me know if they still work

best
My games never have bugs. They just develop random features..
Lots and lots of random features...