Let's say i have a .com domain i want to use here, i installed pfsense with this domain so all my computers are in "home.mydomain.com" now i would like this to work from the outside to so that if i surf to "home.mydomain.com" i get to the router interface, i enabled port 80 in the firewall but i get just "potential dns rebind attack" why? :/
Because that's not a hostname configured as one the firewall should answer on. See System>Advanced, you can fill in your additional name there. Or change the system's hostname to be what its real FQDN is.
Is the user created rule above or below the rules you posted? The default deny rule is above is is not a quick rule so that is going to be the action that is taken if traffic does not match any other rule.
That puts the order on which pfil(9) consumers 'taste' packets.
It was developed first for overcoming some issues but now its not used at all as you can see from the * in ipfw its not a pfil(9) consumer as used in pfSense.
You have control of who does what on your installation.
Kern.securelevel is more of a needed option on multi-user installation while pfSense is not like that.
You'll need to forward port 587/TCP if people are connecting remotely to send email through your server (as opposed to 25/TCP for other mail servers). You'll need 110/TCP and 143/TCP for POP and IMAP and port 80/TCP (and hopefully 443/TCP) for Webmail. I'd highly recommend that you configure your SMTP server and POP/IMAP server to support TLS and your web server to support HTTPS.
Those port forwards should cover your required remote access