I switched to linux less than a year ago after using winblows for most of my life. I found Fedora to be really easy to start with. It's a good mix of stability access to new versions of stuff. KDE plasma is a really good all around desktop environment and easy to adjust to if coming from windows. I'm sure others will chime in with other distro/DE suggestions.

I'd give you more advice, but I still have a lot to learn about linux. I won't be much help with hardware either because I only know about hardware leading up to when I build a PC; I forget most of it shortly afterward.

Linux Introduction

Hardware Support

The situation regarding hardware support has improved massively in the last decade. The only components you may find don't work on a regular basis in a device are the WiFi, Bluetooth, and RGB controls (though these circumstances have also improved massively). I'd recommend installing it on an old computer instead of buying new hardware, as it will most likely work out of the box without you needlessly spending more money. Anything with more than 2GB of ram will likely run fine.

Security and Privacy

There is relatively little to due regarding security. It goes according to the standard don't open dodgy links and the like you previously stated. Furthermore, not only do you not need to install an anti-virus, I don't think any exist for desktop use. Most Linux distributions come with a decent built-in firewall. There is little to no chance of a Linux distribution sending passwords or other credentials anywhere, or granting access to your HDD contents. Most mainstream Linux distributions are regularly checked by various auditing teams, so that is of little concern.

Distributions

A distribution is mostly just the array of software installed around the base system. Some may be better suited to certain needs than others, though (almost) all may be modified to meet a given need. For those not familiar with Linux, I usually recommend Linux Mint for its Windows-like interface, abundance of pre-installed tools/applications, stability, and ease of use.

Applications

Browsing the web:

1. Firefox - Often installed by default, it is compatible with all major web standards (existing and planned.)
2. Chromium - The base for google chrome, for those unable to give it up.

Document Editing:

1. LibreOffice - Supports all major document formats, is preinstalled, and powerful in what it does. May mangle complex formatting on Microsoft Office documents.
2. Google Office - If your already in the ecosystem, it's one less thing to change.

PDFs:

1. Whatever is preinstalled - They are all fine.

Modifying Text Files:

1. Whatever is preinstalled - They are all fine.

Installation

A decent YouTube Guide on it's installation.

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 😀

I'd say Linux Mint feels more familiar to navigate than Ubuntu to newcomers.

Linux is way safer than Windows because barely anyone targets it with malware. As far as safety goes, the main thing is to try and understand what each copy/pasted "sudo" command does before running it. Sudo means "super user do" which gives admin privileges to the commands you are running in command line.

I have never had any malware on any Linux machine I have run. If you're worried because of your threat model (government, hackers, etc), staying within the main built-in repositories will keep you safer.

Things that are community or user-run (RPMfusion, Ubuntu PPA's/Personal Package Archives, AUR/Arch User Repository) are slightly more vulnerable to malicious activity of the kind you're describing, although I have never had a problem trusting them.

for your use case almost any linux distro will work. Pick one of the bigger ones, so support is easier to find. Debian is my personal favorite.

To stay "safe" on linux just keep your software up to date and don't click on any shady links online and you'll be fine.

For hardware literally just google your hardware + linux and you'll get an idea of what's supported.