Skype basically worked like this back in the day. It had it’s ups but for day-to-day users it was rather unintuitive so Microsoft moved to a server system when they took it over. I am pretty sure there are still p2p chat systems around though, I just don’t know any of them by name.
IMO, yes. HDDs are always going to be a bit noisy, but the consumer grades keep it fairly classy. The couple of HGST drives I got from ServerPartDeals are noisy in the “grating” way. The volume is similar but the noise is not in the normal pleasant range. I am only fine with it because my server is in another room.