Spear phishing is meant to target a particular group of people or specific organization?
You should always have a firewall program running. Anti-virus programs can only do so much !
I should, it's my computer, in my home
Personal Firewall
No; the guard between your computer and the Internet is usually called a firewall. An ACL is an access control list, and it specifies which users/machines can access a resource.
The fan on a home computer should run constantly to keep everything cool. Fans will typically adjust their speed based on temperatures, but only turn off when the computer goes to sleep or is shut down.