Guys, this is so awesome, thanks!
Jonathan - re. your initial question - it's pretty standard in most apps that once I select a layer I can move it with the cursors (e.g. Photoshop, Sketch).
In Sketch e.g., I select a layer, can move it straight away. If I want to select the next layer I 'tab' through them.
But thanks so much, Mark - your 'escape' key tip will save me hours of pissing around getting between the windows! Stick it in the manual, Jonathan!