os x web server security question

I am running os 10.1.3 and wanted to know how secrue my system was... I am not an experienced web server adminstrator... just a web designer who doesn't want his site hacked.

I have installed all the updates.

I have a static IP

I allow Web Sharing and File Sharing

I do not allow FTP / SSL / remote Apple Events

I have enabled PHP and have installed mysql

I do not have a firewall running

How secure is my system. Can you recomend a good firewall program. Is it safe it enable SSH?

What do I need to do to insure my system doesn't get hacked.

-Bill