It's all aluminum. We had the opportunity to have some anodizing done for free, hence the black color. As for the weight, I'd have to weigh it, but I'd be surprised if the entire thing weighs more than half a pound. Actually...the servos are fairly heavy...so is the camera...so maybe it weighs a little over half a pound.
The chassis isn't finished yet, so we aren't sure how it will be mounted. However, the intent was to mount it just as it is in the picture.
See this thread for CAD files/assembly instructions:
1351's camera mount