Although this is not the answer you are looking for:
Everyting that you have to transmit to the client to render is on the client. So even if you break the usual functionality of a web browser by denying certain actions, that will not make your application more secure.
There is no such thing as security by obscurity.
Disabling JS will render all your measures void. Even tools like Firebug or Chrome’s dev console will grant the user access to all he wants to know.
If you need to secure your stuff, only display the results and do the processing on the server.
So to come back to your question:
Q: What are the most important keys(keyboard keys) should be disabledin a web site?
A: None!
solved What are the most important keys(keyboard keys) should be disabled in a web site? [closed]