If I do a restore can I recover apps, music, books download since the last backup?

Restore onto a new device? Yes, provided the backup is complete. If it was done using iTunes, with all synch options enabled, onto local storage and encrypted, the resultant device will be identical in content to the original, have done this with an iPad 1 to a 3 and the 3 to a 5.

Onto the original device? Need to persuade it to turn on first else no restoring can be done.

Using iCloud? No idea on degree of completeness. Don't like putting my stuff somewhere beyond my control so don't use it and don't know.