The second one with WLAN, it has a line with “17Mbit/s” written above it. Looking again, that may be the peak line speed. The speeds shown at the bottom does not appear close to the 876 KB/s.
Sadly not. The reporting was done before parallel uploads were introduced. Each starting transfer will reset the progress and start time, but any transfer may update it :'(.
Yes, if there is nothing to transfer, it will of course not transfer. But that would not explain why the overall progress is not moving (assuming it is stuck based on OP).