Oops, the nightingale-and-roses thing is apparently a misremembered quote. The quote I was trying to reference--and I can't find the original either, so, double fail--was something like "I keep trying to write good literature, and it keeps coming out moonlight and roses." My brain combined this with Oscar Wilde's The Nightingale And The Rose, which doesn't deserve it.

It's never stated outright what the choir is, but it's implied that it's a (the?) choir of angels. The character dies onscreen, and the choir is there to welcome him and he can finally see them (including the beautiful alto whose voice he has heard all his life and has never seen, although her presence has been practically tangible to him).