Seedboxes is one of the best things to have at home.
I also have 100mbps internet and I’ve configured router with QoS - seedbox only gets letfover internet, both up & down. I can work, play (mp) games and download torrents at “full speed”, all at the same time because seedbox will never have a priority.
Using this trick I can fully live with 100mbps. Before that I had 1GBPS and honestly - I don’t miss it that much. :)
How is XFCE nowadays? I am on KDE for the past ~3 years and been long-term XFCE user.
IMO biggest KDE advantage over XFCE is that everything literally works out of the box - audio, bluetooth, shortcuts (i hate setting up script yo turn on/off mousepad.
Focus learning on how to install Arch Linux and use it without breaking. This not just gives you a rock-stable distro, but also the required knowledge on to maintain Linux OS.
Or go with “Ubuntu” level of easiness. You choose. :)