Hey mate. Here is Phantoms thread on support crew duties and expectations.
http://www.501st.com.au/forum/showthread.php?tid=6990
We don't really have a dress code as such but almost all of the approved Garrison Members you will see getting around will be wearing the Redback Racing shirts. There are an option once your a full member.
I think the guard is a great choice mate when you get to it. Make sure you sign up to the Guards detachment. Here is the link.
http://www.forcepike.net
Speaking of shirts too, the Sovereign Protectors have one of the best looking racing shirts getting around, second only to the JRS ones made.
One of our local member Phil (Dark Fatherer) has a wicked looking guard. I'm sure he can lend some info when needed.. It would make for some killer photos having two Red Crayons to protect our new Emperor (Tripple9) Courtney!!!