Update re http://www.ventismedia.com/mantis/view.php?id=14635

1) Play to... button is already on the player, just right-click player > Customization and select [x] Play to... checkbox to have the [Play to] button on the Player permanently

2/3) Fixed in 2090, I've made the "Play to" action hotkey-able and assigned 'Ctrl+Shift+P' as the default hotkey for this action

This should be easily possible by adding
hotkeyAble: true
to the action choosePlayer (in actions.js) and then you can manually add a hotkey for this action in Options > Hotkeys

I'll add the hotkeyable property in course of #14635 , but doing this by a script is also quite easy.

That is not possible but I like the idea added as http://www.ventismedia.com/mantis/view.php?id=14635

I would like to choose an output device (such of which are selectable when right-clicking in the player pane) by binding a keyboard shortcut. Basically, I want to toggle between an external UPnP speaker and the PC headset. Using the mouse all of this works pretty well, but I'm searching for a solution for keybinding of this functionality. I would also consider making a script for this, but I didn't find any API hook for choosing an external output device.