You make perfect sense. Regarding the strata on surface shader, it doesn't use the slope restraints, because there isn't a compute. In the texture division youév passed the compute terrain, so there it will use slope restrictions. If you'd add a compute normal just before the surface + strata in the top section it will work.
Second case; you'd need to somehow warp or vector displace the strata as a separate thing and then add as vector displacement in the main line. It is complicated and I am still struggling with this as well, but if you take some displacement, add a strata shader and then turn that displacement total via a displacement to vector or shader into a vecor or color, you can use that to be warped and applied elsewhere. It takes some experimentation though, it isn't very straightforward.