For a basic intro, I would recommend "Principles of Communism" by Engels. It's a super quick read, and it's organized in a FAQ format.
Beyond that, it really depends on what in particular you're interested in. For economics, I can highly recommend "23 things they don't tell you about Capitalism" by Ha-joon Chang (although it's more about capitalism than socialism). For learning about the state, nothing compares to "The state and revolution" by Lenin.
Do you have an old laptop lying around? That's a great way to try out Linux without wiping out your main system. Most hardware, especially if it's a few years old, has excellent support in Linux.
There are antivirus programs for Linux, but I wouldn't recommend it. First of all malware targeting Linux is so much more rare than malware targeting Mac or Windows, but also Linux has some better security practices in general, like not requiring you to run everything as administrator. Most distros will come with a firewall installed that you can configure if you want.
Linux is one of the most reviewed pieces of software in the world. It's used by every major company, and in almost all of the Internet servers you visit. The chances that it's exfiltrating your passwords is extremely low. Linus has even discussed in an interview that the NSA proposed to put a backdoor in Linux, but he refused.
To get started, I would recommend just installing a beginner-friendly distro like Linux Mint on an old laptop or desktop you have lying around. It's actually super easy to jump in, and you'll learn a lot more by actually trying it out compared to reading some beginner guide.
Good luck! I've been using Linux as my daily driver for over 10 years now and I would never go back to Windows ๐