On Windows: for .jpg images I convert to .jng in IrfanView and drop that into Book Details, calibre doesn't know about .jng files
For image formats it does know about you can use this tweak to exclude them - I wouldn't exclude .jpg though.
If you have multiple images put them in a flat zip archive, when you add that to a library it will be stored as a CBZ (Comic Book Zip), there are plenty of comic viewers around, my default is Honeyview.
Audio and video files can be stored in 'book' records, you might want to consider having separate physical libraries. If a book has multiple MP3s I get round calibre's 'only one file of any one format' limitation by creating a playlist file and storing that in calibre - one could do the same for music albums.
If you search this sub forum for "audio" you'll find some threads. And there's some old but maybe still useful links in here ==>>
MP3/Audio Book file-management feature?
BR