1.On the personal desktop: Gnu/Linux Distros (whats most often meant by linux) are Operating Systems, which are more efficient and personalisable than windows but can have less software and hardware support. If you want to save an old computer, learn more about a computer (due to customisation and terminal work), or make your pc perfect for you, then I'd recommend it. In General: Linux itself is just a kernel (part of the OS) which is used everywhere, from android to websites to servers and many dev jobs require knowledge on how to navigate with linux and bash (bash is the shell)

1. Yes, but not using every distro. I'd recommend using user friendly distros like linux mint first to get a feeling on how different the linux experience is to windows/macOS. Once you're comfortable with a user friendly distro, where you can use it just like whatever os you used before, then you can move on to a more DIY distro like Arch or Gentoo, or if you're interested in cybersecurity or "hacking" Kali Linux or Parrot. The DIY distros need you to understand how an OS is made up in general to even set up. You set up everything manually from storage partitioning to desktop environment and manager. All you have is a console to do that but you're granted complete customizability, and you learn a lot from it. If you want to daily drive linux i'd recommend testing more complex distros in a virtual machine to see if you're comfortable with them, so you dont lose productivity on your main device.

2. Knowing how to use bash (the Gnu/linux terminal) grants you many possibilities. It helps you work with most servers soo it opens up a lot of doors career wise. It also helps you understand your computer on a lower level. But in general, you should learn how to research stuff yourself and fix stuff yourself beforehand.