LattePanda MU Boot and Communication Port Baud Rates

I'm currently using a LattePanda MU model running Windows IoT Enterprise LTSC. I have three questions.

1. I'd like to know how to change the PC boot image to something other than the LattePanda logo.
2. The maximum communication port baud rate appears to be 115200. Does this mean 460800 is not supported?
3. If 460800 is supported, how can I set it to 460800?