Subdomains and Static Files

[Weetabix]

After reading this article, I have a few questions which I hope some guru can help me with. The article says to put css files on a different domain, yet the vB option for storing css as files says they must be stored in clientscript/vbulletin_css as CHmod777. How would I go about moving this to a subdomain, and how much of a risk is 777?

Likewise for images. Am I going to have to specify the new path for each individual file, or is there a way to point to the new images domain with a single command or option?

Apologies for the newb questions, it's a DAMN steep learning curve for the uninitiated.

Thanks in advance.