Looks like a great start!
A couple of things I found out from mine: Use a couple of eyebolts linked together for your arm linkages. I used braided wire for mine and halfway through the night they broke (especially at the shoulder joint). I switched to linked 3/8" eyebolts at the shoulder and elbow joints and havn't had a problem since.
Also, I had to use a helmet with a strap to get the most movement out of mine (both turning and nodding). I had tried the bike helmet route and had to go with an open face helmet.

Lastly, get a good belt on your back pack. Mine weighs around 15-20 pounds, which doesn't sound like much until you wear it continually all night. The belt can take all the weight off your shoulders and head and distribute it over your hips.
Can't wait to see how you're coming along with this project. Be sure to post more pics!!!