rlparker: First off, thanks for a very helpful reply. More specifics below.
This is useful information. If I tick "create" in the DH control panel for the user in question, it's not clear to me what I can and can't create in phpmyadmin (e.g., dbs? tables?). Apparently creating dbs is not an option.
This was the ticket. I think before I just found the error message cryptic. The solution was (1) remove the first command (CREATE DATABASE XX....) from the dump file, (2) global-replace my friend's db name with my own db file, (3) delete all the tables in my existing gallery db (all of which were empty anyway), and (4) run the import.
Now I see the whole gallery "structure" on my gallery... but with no images. So I have to figure out how to tell gallery where to find my image files. But that's a question for another forum, I think.
Thanks again to all who replied.