If you watch David's tutorial on hard surface modeling, or the robot one, he shows how to make an object live and pull down the vertices in a way that they conform to the "live" object.

I'd try that for the shoulder plate. But to begin with, you do need to learn some basics like going into face made and deleting what you don't need. You gotta know how to walk before you can run. You should get that Simply Maya robot tutorial, it's really informative.