The He 111P had two internal, longitudinal bomb bays, each with four vertical frames capable of fitting SC250 or SD250 bombs. The (four) doors look like they each have four separate pieces but closeup photos show panel lines, not separate door segments. I cannot post photos, but Revell-Germany have done an excellent job with their 1/32 kit, the instructions are available here:
http://manuals.hobbico.com/rvl/80-4696.pdf Just scroll down to page eight or nine or so.
One of several reasons why the He 111P was discontinued was its limited lifting capability, and external racks weren't going to help - and just add more drag to fight. Another reason was increasing Bf 109 production required those DB601s.
And Merry Christmas!
GRM