Slight necro, but I have news from the Weta workshop! I've been talking with their PR person, and she's been really good about getting me information!
To start things off, Weta is no longer in possesion of their ODST costumes. I am unsure why, and I'm probably not going to ask, either. Rather sad, in my opinion. Those where great suits.
The plates where bolted straight onto the bodysuit, which are custom made BDUs that Weta created. We have no way of locating them ourselves. The bolts where cut short and padded to provide comfort to the wearer. With this in mind, I'm willing to bet that Weta's straps where only for show.
The visors where created with vacuum formers, much like how Rube has been doing it for some time, and how I plan to do it in the near future. Fabric dye was used to tint them.
Those are basically all of the big nuggets of information I was able to procur, and I hope this helps anyone who is currently working on their Weta ODST project!