Testing block of inbound traffic from WAN

Hi

I'm am quite new to Untangle and Linux in general and I am trying to learn how a Good firewall is set up. Please bear with my multiple questions here:

I have read that when Untangle is setup in Router mode, all inbound traffic from the WAN interface is blocked by default. How do I test this fact?

The Firewall app comes with 3 rules already loaded, what are they for or are they only examples?

What is the best practices for configuring the Untangle firewall from scratch, in both bridge and router mode?

My current Untangle Firewall I have changed from bridge mode to Router mode i presume, by setting both interfaces to static. Would the firewall still be effective in blocking all inbound traffic from the WAN interface?

In router mode all traffic from wan to lan is blocked by nature of NAT (Network Address Translation) not the firewall app. If you like to permit some traffic from wan to lan must create the respective port forward rule.
Think in firewall app as ACL (Access Control List) system only.