Well re: this and the several hundred games you are missing, it seems you missed the files in
http://gbamiga.elowar.com/files/Miscellaneous/
These are the more common games which you seem to be missing and Amberstar I believe is in the 1.2 to 1.3 update package.
Edit: and as TCD says you can get the WHDLoads from WHDownload, all you have to do is tell GameBase Amiga where they are, you don't have to set up any drives.