if you're looking to save money, have a look at FreeDNS domains at afraid.org. I use them all the time for one-off projects, lots of public ones to choose from and very easy to update DNS records

desktop environments (GNOME or Plasma/KDE) are pretty heavy, the lightest weight one would be lxqt. it is pretty functional out of the box, but takes some getting used to. the latest version of debian has been out for awhile, go for it!