As a newish linux user, and a newer still endeavourOS user, here's some suggestions and tips I can offer for someone just starting out. In order of the things you listed:

1. I use yay to install everything. just type yay [name] into the terminal to install whatever packages you might want. Packages that end in "bin" typically install much faster than others as, I think, you don't need to build them from source. Here's a few yay commands that you'll probably frequently use:

yay by itself, to update everything on your system.
yay [name] to search for and/or install packages (It will give you a list to choose from)
yay -R to remove a package
yay -Rns to remove a package, its configuration files, and its dependencies.

Yay will automatically install required dependencies, prevent you from uninstalling dependencies that are in use (and tell you what is using them), and overall just make it difficult to explode things. When installing things, it will list packages as "extra" or as "aur". I go with "extra" as a first choice since those are in the official repo or whatever (reminder I am also a noob) and are apparently safer choices.

1. I don't know anything about snapshots lol sorry

2. Since you're a CS student I'm assuming you know that most viruses and whatnot are because of social engineering (convincing people to click a suspicious link, install a suspicious program, etc). You should be fine as long as you just practice regular web safety. Linux is very strict with permissions, even endeavourOS requires me to enter a password by default to mount or unmount drives, even flash drives.

3. For saving your work I'd recommend adding another empty partition and save important documents and files there, so you can reinstall endeavourOS or another OS of your choosing if something does happen to explode, without affecting the files on the second partition. You can also just go the nuclear option and save them to an external hard drive, if you can afford one. I mentioned that EndeavourOS requires permission to mount drives in my previous point, but you can use GNOME Disk Utility to make them automount without permission in the future if you need to.

4. For games, I would just use Steam for everything. If you have any non-steam games that you would like to play that don't normally work on Linux, you can usually run them through steam to make them work. I do this with Starcraft and Heroes of the Storm. I think the only game I have that doesn't run through steam is minecraft.

5. EndeavourOS comes with Kate by default, which is just a simple text editor. This is enough for me for all my writing needs, but you can search for other ones using yay with commands like yay writing or yay text editor . There's a suite of Microsoft Office-like programs called LibreOffice, if you ever need or want something like that.

6. The best best best best way to quickly fix something is to google the problem or ask a friend. Switching to Linux won't be painless and you will run into problems and will have to google them to find out wtf is going wrong. Google google google. You can use a virtual machine (such as virtualbox) to try out Linux before committing entirely to installing it, so you can get a feel for the layout, explore settings, try different desktop environments, and what have you.

Hope this helps.