You should add these:
How they infect your PC?
1. Binded virus - They can bind virus to any .exe files or java files (like binding a rat to minecraft hack something like that)
2. Keyloggers - monitor your keystrokes, steal your save password
3. Macro exploit for docs/pdf/exel

How to avoid them?
1. If you are going to download something from the internet i highly suggest to scan them first here: https://virustotal.com/
2. Updating your anti virus

Heres a useful youtube vid to know if your computer is being hacked: https://www.youtube.com/watch?v=D4GQgDssRWY