You control the camera when you click on the canvas or with mouse right click.
Double click on the canvas will reset the camera, double click on the model will focus on the clicked area.
The Ctrl key is assigned to the masking tool.
The '~' character means "while pressed".

Camera
~Alt + move camera pan camera (if you release alt you switch to zoom mode)
~Ctrl + move camera zoom camera
Shift + move camera Snap to nearest 90°
Space bar Reset camera
T Top view (bottom when pressed twice)
L Left view (Right when...)
F Front view (Back when...)
Arrow keys fps-like movement
Rendering
W Toggle wireframe
Tools
0 - 9 sculpting tools
E translate tool
N invert brush sign
S Color/Material picker (when paint tool selected)
~Alt invert brush sign
~Shift smooth tool
~X edit radius (mouse move)
~C edit intensity (horizontal mouse move)
~Ctrl masking tool
Ctrl + click invert the mask
Ctrl + drag clear the mask
Scene/Files
Ctrl + O or Ctrl + I add file (obj, sgl, ply or stl) or you can also drag and drop on the canvas
Ctrl + Alt + N clear scene
Ctrl + E save as OBJ
Ctrl + Alt + E save as OBJ the current selected meshes
~Shift + click on mesh add or remove the picked mesh to the selected meshes
Delete delete the selected meshes
Miscellaneous
Ctrl + Z undo
Ctrl + Y redo