1, 2--I agree
3--The old Firefoxes are full of security holes that were patched in newer version.
4--Where did you get your firewall info? From independent test sites? I've used commercial firewalls, Zonealarm, Comodo, Outpost for 15 years without a single hacker, and I have no router. And the Windows firewall works in only one direction.
http

/www.matousec.com/projects/proactive-security-challenge/results.php