I've recently switched from Windows to Linux, and I feel kind of "naked", because I don't know what is the Linux equivalent of Windows Firewall + NOD32 + Common

I've recently switched from Windows to Linux, and I feel kind of "naked", because I don't know what is the Linux equivalent of Windows Firewall + NOD32 + Common Sense. I've got ufw and AppArmor installed so far. Is using such a huge hosts file a common practice? Also, what about Flash? I don't want to install it, but some websites insist on it still. What would you advise, folks? I'd appreciate any suggestions.