The number one reference for anything Star Wars is the Padawan's Guide. I'm very fond of it.
Here's their page for that red outfit: http://padawansguide.com/red_invasion.shtml
I have gotten wigs from Cosworx and Amphigory and been happy with both sites. For white face paint, use a theatrical makeup like Ben Nye, Kryolan, or Wolfe. I use Ben Nye myself, and have very little problem with it smearing or rubbing off.
It will probably be hard to find a dress with that kind of shape to it already, but it never hurts to shop around. Thrift stores are a great resource for unusual clothes.