How does oen begin to move any of this to a new OS?

Your apps won't move; the Windows version of say LibreOffice won't transfer to Windows. Instead, you'll install Linux, then install LibreOffice (and all your software) from the Mint Software Manager. Your personal documents and such you'll want to save on an external drive and then copy over once Mint is installed.

Do I need to take an entire day re-installing everything?

So one thing I've noticed about my computing habits with Linux: I install and uninstall software much more casually than I ever did on Windows. I've told stories before about how my father spent about two weeks moving from one Windows machine to another, while I moved into my Linux machine in a few hours, most of which was just letting the computer run while I did yard work.

How does dual boot work then?

Assuming you have a machine that already has Windows installed on it, you will either install a new unoccupied drive, or use Windows' tools to shrink the C:/ partition to make room for Linux. You then shut down the computer and boot to a thumb drive with the Linux Mint ISO on it. During this process, Linux will detect the Windows MBR and can automatically install Linux in dual boot mode. It'll basically shove the Windows bootloader aside and replace it with GRUB (Grand Unified Bootloader) which includes a menu for multi-boot machines so that you can choose an OS each time you boot the machine. Choose Linux, GRUB will boot Linux. Choose Windows, it'll launch the Windows bootloader. There are several tutorials on this, follow one.

How is mint day to day?

I find it quite reliable and stable; I have had Mint Cinnamon Edition installed on at least one of my computers continuously for ten solid years now, it does what I need it to do. It doesn't "just break."

Linux is different than Windows. The file system works differently, things are done in different ways, some concepts have different names. It will take some getting used to. Sure, the Cinnamon desktop looks pretty Windows like at first glance, but there are differences. I have seen folks try Linux, go to do some task, find that it isn't done the way they're used to doing it, immediately rage quit, and then show up on the internet saying obviously false things like "you can't even rename a file in Linux." Sure you can, you're just used to the Windows way of doing things, the Linux way might be different. It will take some getting used to.

One thing I'll note is Linux Mint has a pretty good onboarding process, the Welcome screen shows you how to customize the look and feel and guides you through things like a system update. Definitely do a system update pretty soon after install, before even installing any software.

Do Nvidia drivers work the same way as windows as far as manually searching for them?

This can depend on the distribution. For example, Pop!_OS ships two different ISOs, one with the Nvidia drivers already installed, one without.

On Linux Mint, there is a utility called a Driver Manager. It's included with the OS, you'll open that up, and click the "Nvidia" drivers instead of the 'Nouveau" ones. It'll probably say "Recommended" next to one in green letters. Click that one then click Apply, it'll download and install them for you. AMD is even easier; there's nothing for you to do at all, official AMD drivers are built into the kernel.

Who do I turn to with a question noone has asked before?

You can ask in Linux communities on Lemmy, Reddit, or on your distro's forums. Linux Mint's forums (found on linuxmint.com) are a wealth of knowledge.

Is there like a catalog of commands and how do I learn to use them?

Linux terminal commands are just programs. "steam" is a Linux terminal command, it launches Steam if installed.

There is a built-in manual which you can access with the man command, For example, if you want to read about how to use the list command, ls, you type man ls and it'll tell you all about it. There are commands like which and apropos which can help you find the commands you need.

There are lots of great tutorials on Youtube to get you started learning the basics, like how to move around the file system, create and delete files, etc. It can be pretty fun. You might want to spin up a Linux distro in something like VirtualBox and try one of those tutorials out before you fully install Linux on real hardware.