MPV is a better recommendation than VLC and Although I am a huge open source fan, saying gimp is a good image editor is questionable though.

I have always preferred pinta for normal usage editing and although this might be shunned but idrc, but sometimes photopea can be also good software.

Regarding desktop environmnents, Just try anything you find interesting, KDE,XFCE,Cinnamon etc., you would be shocked by how snappy/minimalist somethings like XFCE are.

Personally I am on hyprland in cachy os.