These days you can merge the SD card with your internal storage which will allow you to install apps on it albeit they will run more slowly off the sd card instead of off the phones flash storage but better than when it could only be used for files

It looks like it has a usb c port on the top and bottom so it might be wired where you can charge with either/or?

The limit on formatting drives as fat32 is 32GB on windows though anything above 32GB and you have to go find a 3rd party tool to convert larger disks to fat32

I know at least at the start some users were confused by the federation process and created 10+ accounts to “subscribe” to other instances plus there have been bots signing up through smaller instances without capcha or email verification so that might explain the discrepency