Hi there, apologies for the delay, it took a bit longer than expected to get the video uploaded.
This should allow you to add references, and it shows how transparency can be used for them:
Imageplanes are parented to cameras so they are used in a slightly different way, but this workflow is superior to "textured planes" in an upcoming version camera creation should be easier than it is at the moment (it's hidden and it only works via Alembic camera import).
You can snap the camera to the nearest 90-degree angle/direction by pressing the Smooth shortcut as you orbit close to them.
There isn't a way to rotate exactly a certain amount of degrees, there used to be a way for 90 degrees but the snap wasn't quite right and I preferred removing it until it was right, this will be added back in an upcoming version too 😉