Good to see this is still going.....
I went to Otakon wearing my recent MK42 build. Found out quite a bit about it and what needed changes.....
I'm just going to warn you about this....
If you actually plan on going to a convention and wearing the suit for any extended amount of time....(ie 8+ hours)....the Tablet will not last.
Powering everything will be the biggest issue you run into. I had an awful time due to the powering scheme I chose at the time. I won't explain further, but it didn't work out well.
Long story short...if you plan to wear this all day, you're going to need a bunch of batteries, or else you're going to not have many LED's or other light up panels anywhere, as it drains batteries quickly.
There was 1 really good video done of me wearing my suit from Otakon....
http://youtu.be/HwJO03P-EBo fast forward to about 2:18 and that should be close to where I start.
Another point I'm going to caution on....and only because I've worked through this. A buddy of mine (who is working on War Machine to go with my Iron Man) attempted to build the switches into the helmet, similar to the way you are doing it. He actually used 'cheek' switches. He found it doesn't work well, especially if the helmet isn't sized just perfectly, and mounted just perfectly on your head. If he smiled (which happened alot....) the helmet would randomly open/close because of it. Or the eyes would turn off/on or change color. Needless to say, he decided that having switches elsewhere (most likely on his waist/belt or chest) would be much more reliable.
Personally, all my switches are in my finger tips. It worked VERY well, aside from all the wiring needed. In my suit I had a single Arduino Mega in my chest that controlled everything LED and servo-wise, with all the battery packs located in the chest. It didn't work out well battery wise, so I've moved to having about 3 or 4 Arduino Micro's throughout the body (1 in each hand, a chest, and a head, so 4 total) and will probably be using I2C to talk between them all. This is still a bit of a work in progress in that sense (initial programming done, but a bunch of cleanup and testing is needed yet).
The Raspberry Pi in the helmet worked out surprisingly well. I was able to easily and clearly view the video feed just fine actually. I was also able to slightly see out of the helmet via the eyes. All in all, that aspect worked well until the power situation got bad.
I would honestly recommend distributing the power throughout the suit. But keep in mind how much everything will draw. If you want to go 8 hours, you're going to need a lot of power. A Raspberry Pi with the camera is going to draw about 1amp@5V alone.....I can only imagine how much a Windows 8 Tablet will draw (even if it has a built in battery, it won't last 8 hours doing what you're looking at doing).
Overall, there is a lot of learning to do. If you plan on going to any conventions, I highly suggest wearing the entire suit 4 or 5 times before going. You're going to want to make changes to make it easier to get on/off, or to move around in, or other various aspects.
As far as the UI, it's awesome. I do like it. I'm still looking into the Raspberry Pi side and hoping to eventually do something similar. I'm going to move away from doing both eyes, to a more google-glass like single eye for the video viewing. That way I can more easily see both out of the helmet, as well as see the video (other issues came up with one of the eyes and viewing).
Lastly, keep in mind what you want to do. If you want the helmet to go up and down, you need to allow room for the entire video-glasses to fit between the face mask and the top of your helmet. This is a difficult aspect to grasp, and I ran into some issues there as well, and would have done it differently if I recognized the problem sooner.
I haven't made any formal posts here about my suit. I've been documenting it mostly via my own Google+ page. I'll have to make a post here soon enough.
Again, I don't recommend the chin switches. It will be difficult and cumbersome in the long run. Another reason I wouldn't recommend it, is because the chin is a terrific spot to add a small fan to incorporate air flow into the helmet, something you're gong to want if you wear it for more than 30 minutes at a time. BUT, if that's what you have your heart set on, go for it! I'd love to see someone make it work. I always had aspirations to make everything voice activated....but the Raspberry Pi just doesn't have the CPU power to do it.
EDIT:One last word of caution....watch how much wiring you plan on doing between different pieces of armor.....the more wires, the more of a pain in the butt it is. I regretted having as much wiring as I did originally. It took about 1 hour to get the suit on just because of all the wiring and such that went on.
