So I'm going to caveat this that I'm not an expert so if I get some details wrong, people should correct me.

Your ability to play games will be effected to some degree, but not as much as it used to be. Because of Valve's work on Proton, about 80% of the games on steam work. You can usethis website to check a community maintained list. Most of the remaining games that don't work are games that the developer went out of their way to not work on linux. This is usually by having an anticheat that doesn't work with linux, or not enabling linux support for an anticheat that does. For playing games not on steam, it requires a bit more effort, but there is Lutris and Heroic for that. Feel free to look into them or ask for more information.

For modding, I don't have as much experience but I have done it and you can. I think how well it works varies game to game, but then again, modding is like that anyway. One piece of advice I've heard is that if you are going to be molded, make the folders not case sensitive. This is because on windows folder names aren't case sensitive, but on linux they are. EG /Folder/ vs /folder/ are the same on windows, and by default different on linux.

For software without a linux version, you can usually find an open source or web app alternative. Microsoft Word doesn't have a linux version, but you can use Libre office, or use the browser version of it, or use Google Docs. For most intents and purposes, this is what you should do. However, you can use a program called WINE to run a lot of Windows software on linux. WINE is what Proton(see first paragraph) is derived from. Similar to Proton, there are limitations, but most come from the developer side these days from my understanding.

The good news is the .NET is on linux, officially supported. I habent checked in a while but i dont think its at 100% parity yet. And a good amount of software frameworks are also available. I've never run into a library or framework that didn't work on Linux that doesn't have a good alternative that does, but I'm not the most avid programmer so someone more experienced can chime in.

All versions of Linux have a program called a package manager, the specific one varies(apt, yum, etc), but they are the primary way you install software one linux. They are like an app store. It installs the software for you and updates it when you tell it to. Core system packages, like the kernel, are also updated through the package manager. Most of the time there is a GUI version or wrapper for package managers in case you aren't fond of using the terminal.

So this is another area where I don't know too much on, but my understanding that linux has fewer viruses and it being open source is a double-edged sword. There are fewer viruses for desktop linix because of the smaller user base. Why would someone making software to harm people not aim for the platforms with larger user bases like windows and Mac? This being said, I think there are more viruses for servers that target linux because of the dominance of it in that space. As for being open source being a double-edged sword, this means security exploits are easier to find because there are more people looking at the code. Both by those who wish to patch them and those who want to exploit them. All my friends and I don't use an anti-virus on our linux machines and just keep them up to date, but there does exist anti-virus for linux.

GPU driver are reliable in my experience, but more so for AMD. NVIDIA has proprietary drivers that some distributions don't let you install for ideological reasons, but they do work most of the time. My computer does run NVIDIA and while I have had issues getting started with the drivers its usually not a problem agyer you get past that stage. Again, AMD is better here and basically painless.

Not to my knowledge, no limux can't damage your hardware. But I'll leave this for someone with more knowledge than me.

The distro I tell beginners to start with is Mint. Installing NVIDIA drivers was easiest on that from my experience, and largely just works out of the box. It has a windows like UI but this is both a good and a bad thing. Good that it will be familiar; bad that you will sometime fall into windows behavior that doesn't make sense on linux. In the past ubuntu filled this niche, and mint is based on ubuntu, but canonical, the company behind ubuntu, has made some questionable choices.

Anyway wish you the best of luck and welcome to the linux community.

Hello there 1- It really depends on your build, distro and drivers being used. Some benchmarks show Ray tracing causes performance drop compared to Windows.

2- There are mod managers here and there but, honestly I don't mod so I don't know anything about it.

3- If a program doesn't have Linux version, there might be Linux alternative. Those alternatives sometimes might not be on par with their counterparts though. Adobe products are one bit example.

4- Applications developed with .NET may be built on Linux through Mono framework, as long as they are developed as portable. For native Windows programs, there is a compatibility layer named WINE, but it won't guarantee that every program will work. It may support games as well, but for games Proton is more preferred. Proton is Valve's official tool anyway.

5- Distributions' package managers will manage updates, either application updates or system updates. Most distros will also notify users about updates, however installing them is up to user's decision. Universal package managers like Flatpak are responsible their own updates.

6- Linux is way more secure than Windows for being what it is. Being an open source does not inherently mean that it's secure. But open source softwares are generally peer reviewed by public and they are often recommended fixes thus if there is any vulnerability, it's fixed more quickly. Antiviruses are not needed, not because there is not Linux viruses though. There is ClamAV anti-virus, also there are proprietary AV applications, if you still need. AV's are mostly ineffective in today's technology.

7- AMD drivers, for example way more reliable than their Windows ones. Nvidia also made a lot of progress in recent years, so yes. There might be still some issues, lack of features.

8- No, it cannot.

9- For a beginner, Linux Mint is and always has been best choice for start, in my opinion.

.NET applications using .NET Core or later are intended to be cross-platform, so technically, Linux can run .NET apps. (The use-case I know is running .NET sites on Linux servers)

Oh, also the biggest difference between Linux and Windows is that you don't go to different websites to install new software. In general you use your distribution's package manager. Think of it like a software center.

Going to a website to download software is a last ditch effort if your distribution doesn't have what you are looking for.

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

A lot of stuff runs with windows emulation as if it's native. It's the same method the steam deck uses and so Valve actively do work to keep it working. The main problem is games with heavy anti-cheat.

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

Generally, yes. I think so.

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

See above.

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

There's .NET libraries for Linux, but things have to be recompiled to use them.

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

The distribution maintainer will issue updates on a regular basis. Update procedure is different for different distros, but all have a push-button update scheme. It's pretty solid these days.

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?

Keep your system up to date with security updates, and you'll tend to be fine. Smaller user base tends to mean that there's far less malware. Antivirus isn't necessary.

Obviously phishing scams don't care what OS you're on, so mind what you click.

Are GPU drivers reliable on Linux?

AMD ones are very solid.

Nvidia ones can be a pain from what I hear, but I don't buy green.

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

No.

That said... You can always wipe a disk when you install an OS.

And also, what distro might be best for me?

Download a few Live-USB images and try them out. You don't need to install them to get a desktop and a browser up. You can see if there's any compatibility issues with your hardware.

Whichever works for you, go with it.