Dont know, what the problem with the GAL is.
Try:
open the address book. on my addressbook you find an entry "lookup". click this, then enter the first name of someone in the GAL.
Public folders:
For public folders of type address book, the besadmin-account needs "owner" permissions for any public folder.
KB19111-How to configure public contact folder synchronization for BlackBerry Enterprise Server 5.0
to publish a public folder, also see this article.