You can see most of the shortcuts behind the respective menu items.
Mouse actions can be found here: http://dynamoprimer.com/02_Hello-Dynamo/2-3_the_workspace.html
You’ll also find some other shortcuts throughoout the Dynamo Primer.
Here’s another useful one: http://whatrevitwants.blogspot.de/2015/05/did-you-know-you-can-select-connected.html
And of course the Esc key which lets you clear the search field in the node browser (as well as toggle to geometry view if you keep it pressed down).