

How do OS updates work in Linux? Is there a “Linux Update” program like what Windows has?
Package managers. Linux had this before Windows. Granted, Linux needed package managers, because of the myriad and complex dependency trees that software can have. I prefer to install software through a package manager because it not only takes care of dependencies for me, it will take care of updates, too. I will only install something downloaded from a website as an absolute last resort. (And then, of course, making sure it’s a trustworthy source.)
How does digital security work on Linux?
It’s rather complex, but you probably won’t have to deal with it unless you have to do some kind of systems administration. On a day-to-day basis, the OS might ask you to enter your password to install software or make an update, and that’s the extent of it.
Basically, every file has 3 categories of permissions: user, group, and others, and each category has 3 permissions: read, write, and execute. This is transparently handled by the system for you, though, and I can’t even remember the last time I had to change permissions on a file. It’s a good thing to be aware of if you have to do troubleshooting, though.
Is it more vulnerable due to being open source?
Just the opposite. Vulnerabilities get spotted sooner because there’s more eyes on the code, and they’re often patched quicker because anybody can submit a patch to an open-source project.
Is there integrated antivirus software, or will I have to source that myself?
I’ve never heard of any distro shipping with antivirus software, but I’ve also never heard of a Linux virus. Of course, I’m sure they exist, but I’ve just never heard of one. I’ve been using Linux for over two decades, and I’ve never used an antivirus or gotten a virus in all that time, and I’ve never even heard of a Linux user getting a virus. Part of that is due to Linux being more secure and part of that is due to Linux being less popular. If you’re writing a virus, you aren’t going to try to jump through the insane hoops of Linux security when you could target Windows which is A) less secure and B) has a fuckton more users.
Obviously, use common sense, don’t install from untrusted sources, etc. etc., but viruses aren’t the omnipresent threat on Linux like they are on Windows.
Considering the comment, I think I’m better off not knowing.