Is there a commentary on the 18 settings of the Kyriale? Something that describes their history, usage, association with seasons, tropes, modes, particular neumes, etc.?

We are introducing Missa de Angelis in our parish as step 2 beyond the Jubilate Deo composite setting. We already know the Gloria. We started the Agnus Dei and are now teaching the Sanctus. The extended melisma on Sabaoth (hosts, as in heavenly hosts) got me to wondering if this is why the setting is named for the Angels.