Actually, lowering the speed limit decreases the time it takes to get to your destination. Lowering the speed limit reduces the need for traffic control measures like traffic lights and will increase your average travel speed.

There’s a good video from NotJustBikes that explains this very well: https://youtu.be/JRbnBc-97Ps

Awesome! I haven’t looked at mint in quite a few years, but I would recommend cinnamon as the default.

MATE and XFCE are mostly targeted towards older hardware.

That’s not a feature of Ubuntu, more so the installer itself. I’m sure many distros, especially Ubuntu-based one will ship with the exact same installer. Idk if mint uses the same installer, but it would really surprise me that the option isn’t available.

Thankfully it’s pretty easy to confirm by yourself. Grab a USB key, flash the ISO and have a look at it!

Yes, any distro with a live ISO will allow you to try it on a USB and dual boot if you want.