Youngster

Hover the mouse over the buttons, if there is a tool tip, it will give you the keystrokes.
Also
Preferences:Shortcuts has a list of tasks that will accept/have shortcuts.
Adjust the assignments to tast
Got hard drives from the old PC? Get a drive clone cable (allows temporary drive connection), then Use the menu on the Library Icon to link the library on the old drive to Calibre. Switch to the drive: Select books:right click:Copy to Library: <the new on on the PC>. Presto...All the metadata and stuff is transfered. You can select in bulk.