Outer corners with plaster -- special corner bead?
it would be difficult to find a lime based plaster. There are places you can still find it in the NE...Virginia limeworks is my preference. They provide the majority of lime based plasters for restoration of historical buildings, re: the whitehouse, the Jefferson estate, ect..
quick set is the bag 5, 20, 45, 90, 120
for your job I would use a 45min quickset
the mud shouldnt have any adhesion problems at all.
the trickiest part of this application is aligning the straight-flex flat pieces to where they aim the creased flex right into the top bead. some finishers would condemn the use of a vinyl bead over metal. I get their argument but what use is strength if you have an obvious eye-sore. Besides if the bead gets beat up, sometime in the future, the fix to that would be a full metal bead from floor to ceiling...which is an easy fix