I mostly use a gui file manager, but when I do use a terminal based one I use ranger. Haven’t tried others, I just like this one.

As other poster recommended, you should by all means install Linux and learn by using it as a daily driver.

What is your end goal with this? Going for BSc in Computer Science / Engineering would enable you to become a developer / computer scientist.

Photo/video/vector editing seems very out of place in your plan. That’s just another domain. If you’re passionate about those visual arts, that’s great and more power to you, but know they’re not relevant for a computer scientist. Src: I’ve been there.

Regarding everything else you’ve said, it seems to me that you’re learning stuff without a direction and just because you’ve heard those things (cs50 / linux), are important. I suggest you choose a moderately difficult task (game, app, tool, website, ehatever) that seems interesting for you to create, (install linux) and start working on it, and focus on finishing it. You’ll learn a lot on the way and gain a broader understanding of how a project is pieced together. Most importantly, you’ll figure out what you don’t know, and thus eill have a direction going forward.

And don’t get me wrong, you’re right, you can gain a lot of valuable knowledge by going through cs50 or learning to use the linux terminal, but it’s not really useful unless information, unless you apply it to a project.