Questions about Netgear Gs110mx-100pes

You can connect to this switch 2x 10GB and 8x 1GB at the same time.

Ports 9 and 10 can be used up to 10 GBit... so, for example, you connect the 10th port with the 10 GBit port on the Salt router and then have 8x max. 1 GBit (ports 1-8) and possibly another 10 GBit on port 9 for another router as an uplink... or just 1GBit for a normal device... Normally no PC, scanner or printer has more than 1 GBit anyway...

It is best to connect the 10GBit ports with each other to use the full bandwidth between the switches. But it can also be any port.

I have installed both switches in my home to have a 10Gbit connection from the office (1st floor) to the basement to the Nas. This works surprisingly well with existing cabling (approx. 15 years old). The difference is that one switch is unmanaged and the other is smart-managed. This means that the MX does not have a web interface for making settings. Connect the power, plug in the mains cable, done. With the other one, you can set many things on the web interface: IP address, interconnect ports, set speeds etc. I use it in the basement to connect to another switch, another NAS, etc. So: Plug and play = MX, plug and configure = EMX. I strongly suspect that the actual hardware is identical.

Yes

This switch has neither PoE in nor out.

I wouldn't worry about the waste heat... In my case, the switch in the distribution box is only lukewarm when fully occupied.

Unfortunately this is not possible, you are limited to one additional device at 10gb/s. The other ports are limited to 1gb/s. I would opt for the Netgear MS510TX which has 2 extra ports at 5gb/s.