Interesting discussion, some quick remarks (doesn't claim to be complete) concerning the current configuration:
- Range: You have to offer more. Take a look at the history of the Mercure and it's lack of range.
- Weight: Your assumptions concerning the OEW are very optimistic.
- Wing design: Right now not comprehensible.
- Space: During the detailed design-process, it's much easier to scale something down, than adding additional things. From my point of view, there is a lack of space for everything, especially for avionics and several supply units. Possibly, parts of the main landing gear an the wing will extend into the cabin and you have to remove some seats and you have to add an extra row: Add one or two meters of length to be prepared.
- Emergency Exits: The current configuration is inflexible for cabin design. And try to avoid the use of emergency slides.
- "roof top windows": You have allready mentioned the problems concerning high tension. It's not impossible to install some windows, but be prepared for a lot of problems.