As far as cutting up the 3d models, I have heard netfabb has this capability though I have not used it. That could be a place to start looking.

However, if I was going to do this as quickly as possible, I would remodel the exact logo you have above in google sketchup. You can import the picture on to the top plane and use the free form line tool to trace the shape of the logo. Next you can use the pull tool to make the emblem as thick as you'd like. Then you can export the STL files individually by selecting the piece you need and clicking export selected geometry only. Doing this would allow you to have the 4 separate pieces. You'll need to install the free STL extension inside sketchup. If you need any help with sketchup I'd be happy to help!