1) No chance... I just tested a plain butyl tube and that wont fit.
2) Im still riding mechanical ... can't say?
3)From everything I have read IA1 and IA4 are the same frameset
4) 24mm powermeter, no problem
5) Totally exist.. examples bottom brackets ,ceramicspeed and hawk racing both make a bb30.24 bracket
6) Brakes Initial brakes got beat up a lot. Then they replaced the arms with ceramic and the increased the strength of the spring...I think the brakes have been great since then.