Sorry, but I have so many questions;

Assuming I want to preCache the source of my each wedge for simulation in TOPs to disk .

Will TOPs just read the wedgeIndex value to pull the correct source for correct wedge?

Something like below

No it won't unfortunately. If you want to generate more secondary wedges based on the geometry that was written to disk, you will need to put down a Geometry Import node, set the Work Item Generation to “dynamic”, and the Geometry Source to “upstream result file”, as you are now depending on the bake results of upstream workitems to make determination on how many workitems to spawn downstream.

I am having trouble getting this to work. I have geometry written out and based upon this is I want to create @wedge wedges based on how many points it has. I can't upload a scene, but it is something like this

Guide Geometry ROP Geo Output (to find how many points it has)
-
Geometry Import (with work item generation to Dynamic and, Geomtry Source to Upstream Result File, Load Geometry During Cook checked, and pointing to the correct External File Path, and have set Item Index to Upstream Item Index)
-
Wedge driving @wedge (which picks in number of points from the Guide Geometry, and the same file that the Geometry Import is importing)

No matter what it doesnt set the @wedges to number of points in the Guide Geometry. I dont get any errors, just 1 work item.
Everything is set to dynamic.