The extra two pieces above the frame are the bottom bracket and crank spindle, I have yet to join them to the frame.Ok I'll take a guess.
The short tube looks to small to be a bottom bracket,but I can't see in my head how it could be a head tube or where you would sit. Unless of course the short tube is where the seat will mount.
The big curve looks like it might follow the rear wheel,so maybe the excess is a crazy sissy bar.
Am I even close?
Also the frame is only half built at this point, I guess what is sitting there is roughly equivalent to a front triangle, I still need to add the rear triangles/canti bars and the seat...
Some of what you said is very close to how it will be, other parts... Not so much!
I think you will work it out pretty quick Falstaff!
Luke.