Blaven, with respect to your 2nd question, all Ethernet Switches operate at an internal frequency of 25MHz, and have nothing to do with Audio clocks at all (either base redbook rates, or 10MHz reference clocks). Additionally, Ethernet being an asynchronous packet-based technology with very robust error correction at multiple layers, their internal clocks don’t need to be very precise at all. Which is why even the cheapest Ethernet switch can provide totally error-free operation for years in any normal home.
As far as the regular Music streaming services and protocols (e.g. DLNA/UPnP/Roon/RAAT etc.) are concerned, adding additional clocking to consumer Ethernet switches does absolutely nothing. Unfortunately theres just so much misinformation out there on the ‘net which only serves to feed an audiophile’s imagination. I highly recommend that you read dCS’ series of technical articles (by James Cook), and specifically the one about asynchronous sources in relation to clocking and jitter.
Enjoy 