I wouldn't expect too much audience noise. Chamber music audiences are usually pretty good about being quiet for the most part, with exceptions for a few coughers, page rustlers candy un-rappers and fidgeters. Those nice seats look new and squeek free. In the front row the issue is less critical than a row or two back. Running the mics low can also help since the patrons in the front row will somewhat block and direct audience noise from behind, but you'll still get good room reverberance from above.
Hard to say on the curtains or shell without hearing them play the room, those early reflections can really go either way. IME, I sometimes find shell reflections screw up the sound at the recording position for things other than choral groups, even though the shell can make it easier for the musicians to hear themselves and play well.