Adding commands to shutdown and reboot

[utu]

to change volume i just mess around with the LXDE pluginvolume.png

I have no experience with the png you show for a Volume Control applet.

The one I use is the standard lxpanel applet supplied with Knoppix.
If missing, thie applet I use may be added with
Right Click lxpanel>Add/Remove Panel Items>Panel Applets>Volume Control>Add

You might try that.