#1
Sarasi1, I wonder if you are aware the early low structure that eventually became the iconostatsis is also the origin of what became the altar rail in the Roman Church?

I apologize if what follows is old hat for you, but proffer just in case it is new. Early imperial churches in both the Old Rome and the New Rome had essentially the same liturgical architecture. 

The apse had bleacher-like stone seats for the clergy, with the bishop at the top centre. The altar was in front of the apse and it was surrounded on three sides with a low barrier (roughly 3 feet) generally of solid marble, with the fourth sided open to he apse. The ambo was a pulpit- like structure in the middle of the nave. In had stairs on both sided (that is, facing the sanctuary and facing the central entrance into the church. There was a "runway" (a slightly elevated walkway from the centre of the sanctuary to the ambo, and regularly the the barrier around the sanctuary was extended down both sides of this runway.