Hi Arlberg and welcome to the forums!!
1.) I have not had yet a Stages in my hands in person and do not know about its dimensions, but please find some pics I just took of a VIAL evo with installed Dura-Ace FC-9000 chainset: clearance VIAL evo/Dura-Ace 9000 cranks
2.) There also are (ging to be) complete bikes around the VIAL evo, based on different build kits (shifting groups, wheels, cockpit etc.). We have not published the build kits just yet (Eurobike being the target here), so please inquire directly for an offer. Shifting components are available from either Sram or Shimano with a Di2 of course being no problem at all.
3.) The current frameset i(frame as well as both forks) s solely compatible with rim brakes. With the introduction of disc brakes we may eventually see new standards (rear hub width, rear/front axle systems), so without having certainty about these from a current perspective it does not make sense to us to commit ourselves to a certain construction just yet. Rumours are the standards will be finalized at or around Eurobike which is when we will start adopting the VIAL evo to a disc-specific model as well. I do not think hybrids make sense here. The disc model may then already become available in spring next year.