Are you planning to run backups from discs or an external drive? Scene releases from the era were .iso backups of retail discs. I can't quite remember for sure but I think .wbfs was for WiiWare i.e. smaller downloadable games. I used to just burn the .iso to a DVD and run it through the homebrew channel.
Torrentleech has a Wii category, just check it isn't a Wii U game