FLAC definitley has metadata. Try Mp3tag - the universal Tag Editor (ID3v2, MP4, OGG, FLAC, ...)
and download MP3Tagger, its free and it updates/creates tags for flac,ogg,vorbis,mp3,m4a, and many others. You can add several pics and the rest. Try VLC to play them. VLC plays everything and it is also FREE!!