Input

Stylus Button: Drag Canvas
Shift Stylus Button: Rotate Canvas
5: reset rotation to north
Control Stylus Button: Zoom Canvas
Control Tap: Select Color
- Control-Alt Tap: Select Original Layer Color (discounting layer opacity, merge method, etc)
Back Stylus Button: Pen Wheel
F: Fill Tool
B: Brush Tool
Shift Tip Drag: Brush Size
Transform -> Control Rotate: Rotate in 3D Space
Control M: Non-Destructive Mirror
Shift Backspace: Fill Layer (or selected area) With Color
Hover R: Find Highest Layer With Paint

Interface

https://krita.org/en/features/
Alpha Lock is to paint on pixels that already have paint in the active layer. (shift backspace will only fill painted pixels, also)
Inherit Alpha applies the alpha of layers below this layer
- this layer can have more painted pixels, but they will not be visible with Inherit Alpha turned on.
- Test and discover the layer impact. Artists don't know how to express booleans.