Cantus Selecti has a section at the end with notes on each piece...

Rhythmus de Mysteriis B.M.V. a Guidone de Bazochio, cantore Catalaunens († 1203) compositus (Variae Preces, 1892, p. 212)

As for Translations, All the Roman Hymns are translated by Britt, The Dominican by Aquinas Byrnes, I have yet to find a book with the other Orders. Of course St John Henry Newman, Neale and Caswall have books with translations and Dom Gueranger (in the form of his translators Dom Laurence and the Nuns of Stanbrook also translated many Hymns. Although most Latin Hymns have not been translated!

I have had a quick search of what books I can easily search and have not found a translation...