How to update to latest packages with pkg_add and keep system source stable

[Tim]

Hello
 
I am a new FreeBSD user. I have installed the latest production release 5.4. 
 
 
Two questions I have are:
 
1. How do I update to the newest binary packages without using ports? I have a slow computer so compling through ports is not fun. When I now do a pkg_add -r firefox I get version 1.0.3 and not 1.0.4 which I've seen exists as a binary package via the web inteface. 
 
2. I want a stable system. I understand that upgrading system source to FreeBSD-STABLE is in fact not stable at all. So what efficient method exists to keep my system secure and stable? 
 
Thanks!