1) We wrote it this way to work with the OpenGL standalone renderer we were working with.
2) This was probably due to the separation of passes within RM (each pass is treated independently).
3) The COLLADA 1.5 support was never 100% completed – however, we mistakenly released the wrong COLLADA Release notes.
4) There is no plan to continue developing RenderMonkey at the moment.
Thanks for your reply. It's sad to hear though development of RM stopped. I guess there is no chance to make it open source?