This is a very interesting idea for a project and something I think many choirs would be interested in performing! Was there a reason you particularly wanted to restrict yourself to "calm, short pieces?" I'm curious what other texts you are thinking of incorporating; these first two are certainly a good start! It's a shame that Cantai doesn't give the vocals a more monumental sound, but it's still helpful for a sense of how everything goes together. I particularly like the little harp arpeggios for their sense of wonder. I'm not sure you need to specify the number of choral singers on the first page of the score. Instruments are good at being loud, so choirs that work with orchestra are good at maintaining membership big enough to balance orchestral forces. And the choral singers generally aren't paid, only instrumentalists and vocal soloists, even with major orchestras. So usually the paid orchestral parts are the only ones given a number of players needed. Nice!