Wow, you're constructing your own engine. Very ambitious. I wouldn't mind being informed of details and progress on that process. (In fact, I wouldn't mind actually participating in something like that, but my mathematics background is too weak, and my vc++/c++ skills need refinement.)
Concerning source requests, I'd be very pleased and impressed with any details on how to make .wdl appear more object-oriented, via the sdk or something else.