Yep that relay should be fine.
Those projector style LEDs would be good for reverse, as you want the light projected outwards (to see). For the turn and brakes, I'd rather have something that fires sidewards/backwards so light is reflected off the housing rather than projected outwards (to be seen).
Something like this. Will have to figure out which ones will work best in the housings (Philips make a few different styles now).
But hey, that's just me.
Des, got some more shots of your light output? Looks pretty great.