Greetings,
I put your post into its own thread, so it can be better addressed without a mix-up of too many different posts in a single thread.
Nothing can replace Foobar2000. Using this music player since about 15 years and can’t miss it. 
That’s where the AppImage things have their downsides. If you just plainly install something from APT, you can just run an apt update followed by an apt upgrade and there you go, your software is updated, if there were updates available, in the first place.
There are tons of tutorials about this, but, to be honest, none of them are really beginner friendly, at least to my knowledge.
They just lazily dump all common commands into an article and call it a day, instead of explaining what each thing means, instead of only what it does…
That sounds just like the life of a Linuxer. It’s “normal”, according to them.
Indeed. That is actually a huge issue in the Linux community. There is an amount of beginners, and then there is a huge elitist pile, who do not want to word it nice and easy for beginners, because they want to be so “pro” and whatever. It’s a problem of mindset and the inability to think human, instead of only like a Computer Scientist or DevOps specialist.
If the mindset would be more open to less techy people, Linux would be much more popular. It would also have a GUI tool for everything, just like Windows does. In Linux you have to do a lot in the terminal, if you want to do anything that is slightly more advanced than changing your wallpaper or opening the browser.
There is a sad truth to this, as it is often the case in life: You just need to practice and gain experience. That’s it. There is no shortcut around it. You can’t just read the LFS book and be done with knowing Linux. You need to live it and get to know it, manually. This is the only way to actually understand it. However, this, of course, takes a lot of time…
I disagree with that. Learning Linux is like learning a new language. The worst thing you can do, is always think in your language and then translating it to the other language, in your head, every time you want to speak. This is an extremely bad practice.
The best practice, when learning a new language, is to think in the new language, in the first place. Think like someone who uses the language as their default. This is the real way to learn a new language.
Same with Linux.
You have to think in Linux and then you can learn it. If you think in Windows and try to translate it, it won’t work. They are just too different. Try to find a registry on Linux. Try to find proper not-outdated GUI applications for Linux. 
Sure, there are things, that are similar, but if you compare them a lot, you will find out, that it’s not helping you, because even if they seem similar, like, for example, Systemd and Windows Services, they are still fundamentally different.
Therefore, long story short, if you want to learn Linux, you have to learn from a Linux perspective. Forget what you know about Windows, when thinking about Linux and trying to do anything in Linux.
This is actually one of the very few aspects of Linux, which are actually portrayed worse than it is actually the case. The reality is, that like 90% of distributions are more or less the same. They just look different. Sure, there are even differences between Mint and Ubuntu. There are. But they are so minor and exceptional, that you can more or less ignore them. For example, if you used Ubuntu, you will immediately get along with Mint, without any learning you have to do. They are pretty much inter-changeable.
Similar with other Ubuntu derivatives. They look different and smell different. The under-the-hood part is still 98% the same stuff you get from the original Ubuntu.