action when keyboard pressed:
1) you can set the focus active on the e.g. stop button - using the
proberty node - when you press enter the value of the stop button will
change.
2) you can set a shortcut to the button, in front panel: right mouse => advanced => key navigation
now your other questions:
why you want to change the file when you write a comment?
and rename the new file?
i think for this you must use the file name field