Linux

Will my ability to play games be significantly affected compared to Windows?

Most if not all single player games will work without an issue on steam thanks to its integration with proton, if you use something else you can use lutris to fill in the gaps there.

Can I mod games as freely and as easily as I do on Windows?

I see no reason why you can't. Hopefully someone else can elaborate on that as I haven't done that in forever.

If a program has no Linux version, is it unusable, or are there workarounds?

It can be unusable. There could be workarounds but that would depend on how dirty you want your hands to get. You can install windows on a docker container and use that to fill in the blanks if needed. There would also be some linux alternatives of some apps which would be worth investigating and learning.

Can Linux run programs that rely on frameworks like .NET or other Windows-specific libraries?

I think dot net has been open sourced but you can get dot net apps using Mono.

How do OS updates work in Linux? Is there a "Linux Update" program like what Windows has?

You use the package manager, which varies based on linux distro/flavor. It's your best friend and you'll get 90% of your apps that way too. Upgrading depends on whether you are using a stable distro which is like say windows 7 and you'll have to upgrade to windows 8 (omg lol) you'll have to follow the procedure of your distro, It's usually well documented and should be fairly easy if your sticking to the flavor of Linux you're using. If you're using a rolling distro/flavor then you'll just keep your packages up to date regularly via the package manager. Be warned sometimes you'll have 300+ packages to upgrade so if internet is spotty may not be your thing. But it's a great way to ensure you're getting the most out of your new exotic hardware.

How does digital security work on Linux? Is it more vulnerable due to being open source? Is there integrated antivirus software, or will I have to source that myself?

Use clamav, make it watch the home directory /home as that's where you as the user have the privilege to write data to. Never run as root unless you're going to be extra careful. Also don't run scripts you don't understand or aren't well maintained in a public repo (at that point you as a newbie would be relying on community to determine if something is good or bad think of it as the upvote and downvote system but with more transparency)

Are GPU drivers reliable on Linux?

Yes, even the nvidia drivers are reliable. Just a pain as you'll have to reinstall the kernel module, the component that integrates the driver into your new kernel, after you upgrade kernel versions. Kernel is the thing that does all the low level handling of your devices.

Can Linux (in the case of a misconfiguration or serious failure) potentially damage hardware?

Most hardwares/processors now are designed with failsafes to throttle when there's not enough cooling. Please elaborate a little on this. You can break software but I think hardware should not be. Hopefully someone can elaborate as well.

And also, what distro might be best for me?

Linux mint, it is well documented, doesn't have the snaps that Ubuntu is pushing, its user friendly. Similarly fedora. You can try one of those immutable distros which may give you a more stable experience as it rolls back to a stable state on an update failure.