Thank everyone for the answers! Yes, I didn't know about the automerge option, but I would still prefer a more fine grained control.
Perhaps having these options for duplicates:
Replace
Keep both
Merge into older
Merge into newer
Do nothing
The replace options might be handy when you know you're adding a new revision of the same book.
Helen, that would be great! Count me in on dreaming
I will play with the author sort preferences, thanks. Still, I cannot think of a situation where one would prefer a strict ASCII sorting of non alphabetical characters, rather than ignoring them altogether. For example, the leading "¿" and "¡" found in Spanish books, or the leading "#" which might precede a number.