In the 10.3.0 release, we have added some keyboard shortcuts for navigating within a test case, using the arrow keys to navigate up and down and expand and collapse parent steps, and we intend to add more over time.
The copy/paste keyboard shortcuts are also a great idea. We've also thought about adding the [SHIFT] key to let you select a range of steps (rather than clicking steps individually), using keyboard shortcuts to help select commands in the new command interface, and using keyboard shortcuts to interact with the Local Player controls.
If anyone has additional ideas/suggestions for keyboard shortcuts, please add them here.