maybe look into udiskie for automounting/unmounting your external drives. It notifies, ejects and powers them off nicely with a terminal command you could alias, script or keybind to something real simple. Then in ranger I have 'gm' set as shortcut to go to media. I don't need the GUI file manager that often anymore.
After some time living with Gimp/Krita etc. you will learn to do the things you did with Photoshop. It does takes some time and research/learning. I was real comfy with PS and do miss it but the more I've gone without, the more I've found ways to tackle the things I need to do with alternatives.