What’s the easiest way to create a master/opacity fader for a layer? Can’t seem to find a texture opacity node or something.
The easiest way would be to use Channel multiply node and adjust the last float entry (A) to something less than 1.
These features have been much improved in v3.0.5. Render to canvas node now has an Opacity input.
That’s particularly useful if you combine it with one of the Fade nodes, for example, Layer fade in:
More about fading the content in and out can be found in this user guide.