1. I would like to have a shortcut to create virtual copies.
The menu doesn't mention one, Mr. Evening's Lightroom book, doesn't. So maybe there isn't one.
Can you customize keyboard shortcuts?
I don't think that you can customize shortcuts.
2. How do you erase virtual copies? If you hit the delete button, Lightroom proposes to erase the master file. Which, of course, I do not want to. I couldn't find a "delete virtual copy" item in the menu.
If I select the virtual copy and hit the delete button, LR offers to erase the virtual copy only (Message: "Remove the selected virtual copy from from Lightroom"). Are you sure you selected the virtual copy and not the master file? Are your files arranged in a stack?