What a brilliant and interesting post, Nani Nana!
Sorry my answer is so slow -- I honestly didn't know where to begin answering your interesting questions, but of course waiting a day or two didn't do much to help me...
I'd love to answer your questions, and I will -- but right now I'm so busy and I find it difficult to write anything even close to what I'd like to say. So instead I'd like to post Mozart's Mass in C Minor, and hopefully it will bring you (and anyone else peeking in!) joy.
This is from a concert I attended in December '08, and since I was there I can say the recording is absolutely brilliant. Here's the first part, up to & including 'Qui tollis'. The rest will come in the next post. Enjoy!
(Your idea about posting the vids behind spoiler tags is excellent!)
Mozart, Mass in C Minor (K 427) -- The Royal Stockholm Philharmonic Orchestra, The Monteverdi Choir, The Eric Ericson Chamber Choir under Sir John Eliot Gardiner.
(Soloists - Miah Persson, Ann Hallenberg, Helge Rönning, Peter Mattei)