Here you go
8760-radiation study per facade-internalized.gh (557.1 KB)
#1 See my approach in the script, might not be the best way, but I’m just multiplying the results by the face areas and doing a mass addition and checking the units.
#2 Honestly rather than looking at what you did wrong, hopefully my part of the script just shows how to do it correctly. I was confused how you were creating your analysis points. I would use the LB grid component instead to then generate a HB sensor grid.
#3 It looks messed up because your results don’t match your mesh, same explanation as #2
#4 Personally I think the way it works atm is sensible. If you wanted one single result you could create just one analysis grid, instead of one per facade, which would give you the combined result (HB Annual Irradiance, radiation output, multiplied by the face areas from LB Generate Point Grid)
Edit
I just added an edit that converts from mm2 to m2 to give the correct kWh for your file units.
8760-radiation study per facade-internalized.gh (552.5 KB)