I suggest reading through multiple answers despite everyone answering all your questions, this way you get the most complete answers. As such, here's my two cents:

1. Yes, search for "Widgets" at Gnome's official website to see: https://extensions.gnome.org/

2. Depends on what you mean by "problematic"? My laptop refused to go to sleep because of a setting in the wifi card, but once I changed it I haven't had any issues. You may also find that some of your hardware is nonstandard, and therefore requires extra steps during installation.

3. What do you mean "minimum"? Because I installed Debian headless, and starting with nothing but a command-line and the system utilities and nothing else installed is what I heard, but maybe in your mind it just means a graphical desktop and nothing more. If you did mean that, you could try something like MATE for your desktop environment, or XFCE if you want to learn by customizing. If you're feeling really adventurous, use SwayWM

4. Depends on how it came installed, but generally it's easy. Most of the time, starting out it will be as easy as running the uninstall command for whatever package management software installed it.

5. "Rooting" a device refers to installing untrusted firmware on SoC devices. Unless your laptop is a chromebook, you probably don't need to worry about that. Dual-booting Windows and Linux won't stop Windows from updating, nor stop whatever application manages your firmware from working in Windows, if that's what you're worried about.

6. It depends on your distro and its package manager(s). In Debian it's as easy as sudo apt install <Desktop Environment> and then logging out, changing which DE you're logging into, and then logging back in. Most are going to be that way

7. Lazy answer: don't worry about it, and don't worry about it. If you're the type who wants their PC to "just work," it's behind-the-scenes stuff that will never apply to you. If you're prepared to get down in the weeds, occasionally break things, and customize every aspect of your OS, then you'll learn when it's relevant. If you're saying "Lazy question" and not showing that you already did some research on the topics, you're most likely in the former camp; this isn't a value judgment, just an observation.

But, since we're all still nerds here regardless of what we're nerdy about, and since learning almost never hurts, I'll throw some vocab at you to get you started:

Wayland is a specification of how software should display things on the screen, it's the generic blueprints of how Display Servers and their Clients should behave; Wayland is seeking to replace the X Window System specification, and specifically the popular Xorg Server implementation.

Docker is a containerization platform (software ecosystem). Containers are essentially a small subset of Virtual Machines (or VMs) which are Guest operating systems that run within a separated off environment from your Host operating system. On Linux, features like namespaces, cgroups, and chroots are used to achieve this effect. Containers tend to use less hardware than Hypervisor-hosted VMs, but also tend to be single-purpose systems.