Is there a way to play video on a secondary screen/monitor whilst keeping the controls /interface on the main screen, kind of like Powerpoint's 'presentation mode'?
Absolutely. MC excels at this. And, yes, the answer is to use a Detached Display:
http://wiki.jriver.com/index.php/Detached_DisplayThis allows you to use the entirety of MC itself, in whichever mode you want (Standard or Theater View) as the "controller". The "display" pops out (with no UI left on it at all, to speak of) and you can move this around independently of MC itself, but you still use MC just as you would normally to control it.
MC can have multiple Detached Displays, running simultaneously, one per-Zone. And, they remember (again, per-Zone) their last-used size and screen position, including whether they were full-screen or not. So...
1. Make a Performance Zone.
2. Hook up the projector in extended desktop/non-mirrored mode.
3. Play something in MC on your laptop's screen and detach the display.
4. Drag it to the projector.
5. Make it fullscreen or arrange as needed.
6. Close the display (by clicking the corner X, right clicking on it, or hitting the "click here to bring back" link which appears in all of the usual playback displays).
7. Now that zone will always go fullscreen (or to that last window size and position) when you re-detach it, so long as the external display is still hooked up. Pro-Tip: Control-6 opens the current zone's Detached Display immediately even with playback stopped.
Before the "event" begins, you just open the detached display. If there is nothing in Playing Now, it shows black window with a very subdued MC logo. If you're real into it, you can even replace the logo with a transparent image (or your own logo).
All of the "regular" ways you can control MC apply equally to MC with a Detached Display open (JRemote/Media Network control, command line, COM, scripting, another copy of MC over the network, whatever). Any of the
Display Plugins (stuff you can do in a "display" in MC) will go there when played.