No idea about the Mac bit, but I'm using it on a PC, so I too can give a little database app to one of my clients.
Re. your hold on - the answer is yes. Copy all the online files and folders, and the database tables of course. The tables would need a database dump with create and data, then just run the sql through phpMyAdmin (in the system as well!) and check the DB connection (location, username etc) and it should work.
If you were even sneakier, you'd remove phpMyAdmin from the folders you passed to the client, so they can only use your web interface.