Sorry for the delay answering questions, I'm in workshops for the next couple of days so not much (if any) access until later in the day/evening.
Uncovered Chicks - not a problem. Adults are there to keep them warm, cool, dry. In the mornings, the ledge heats up in the morning sun as does the wall which re-radiates the heat back out from about 8:30-9:00 am onward until a bit after the sun has gone behind the building. So when you see the chicks uncovered, there will be at least one adult while the chicks are this age within a few feet of them at all times. The other adult is usually not far away either. If they are "off", its because the chicks don't need them to keep them warm, cool, dry.
Sound - have mentionned this before in another thread, but this is as good a time as any to reiterate. No sound at the Radisson - ledge is a good 50 feet away from the nestledge and there is no way to filter out the environmental noise (traffic, sirens, wind, etc) so you can hear the birds other than when they are broadcasting very loudly. In the nestbox we have a problem with wind howling through the louvres so that will probably not be a good location either for a mike. The Brandon nest however would/will probably be perfect when we manage to get a cam going there ...
Think those were the only unanswered questions so far ...