Shortcuts
You can find the shortcut cheat sheet by clicking on the "Shortcuts" button at the bottom left of the main Capacities window.
You will see the full list separated by area, or you can search to find what you're looking for.
Shortcuts cannot be customized at this time. If you'd like to see this added to Capacities, feel free to vote on this ticket.
Overview of all shortcuts
Here is a graphic with all supported shortcuts on Mac and Windows:
All shortcuts as PDF
And here is the full list of all supported shortcuts as PDF: