Customize some keyboard shortcuts

[Pétùr <peturvilj gmail com>]

Hi,

I'm having a hard time to configure the keyboard shortcuts of my new gnome-shell 3.22 session.

I would like: 

 1- To bind "Emacs" to "Shift+Enter". For some reason it seemes to be impossible to use Shift+enter for a shortcut. Is there a workaround ?

 2-  I used to have volume down and volume up in Ctrl+PageDown and Ctrl+PageUp. I tried to use "amixer -q set Master 5%+ unmute" and "amixer -q set Master 5%- unmute" for this (my config in Xfce) but both cut the audio (while working from a terminal).

3- I am using ncmpcpp (mpd client) for music. I binded my multimedia key to "mpc play/prev/next/toggle". It works but I don't have notifications and the multimedia keys will not work anymore with other software than mpc. In Xfce, I could have both mpc and the default behavior of the multimedia keys, is there a way to have the same?

I would be very grateful if the list could help my with this three issues. In a more general way, I am interested in alternatives to the gnome default shortcuts manager which allows more customization.

Pétùr