Creating multiple surfaces from lines

Hi there

I am pretty new to grasshopper. I work as a structural engineer so I don't use it that often.

I have a frame that will have some cladding offset 60 mm from the frame. I am using grasshopper to create the cladding as surfaces.

Attached is my rhino model and GH script. 

I have managed fine if I set 3 lines at a time creating 1 surface. I then bake this surface and do the next. You can see where I have done this in my attached rhino model.

My question is can I create all the surfaces of the frame in one go? Or do I need to create them individually?

And once I have, can I create a Polyline around my surface. I know how to do this in rhino just wondering if it can be done in GH.

Will save me LOADS of time

Thanks

Ruben