I think your tips in hole a good. But i would just like to add 1 or 2 things.

add#1-
Learn about how the web works, and about routers/firewalls. As well as vpn's and ssl. This is a neccesity. Wardialers are a thing of the past.

add#2-
Learn how to make a box succure. If you now how to pertect something you know that it's weaknes's are.

not a lot of info, but I think it will lead you in the right direction. personally, i keep my company network up and running and these are the things that I need to know.