Yes good post Dave.
The rules are completely driven by where the cr is needed for, indycars have realy compact noses(the chassis is out of the irl time) to reduce drag for ovals, they nearly have no diffuser and for road courses they generate almost all their downforce ut of the wings.
The ground effect cars didnt have front wings anymore as it wasnt needed, the cars had very long sidepods to generate more downforce, and the only reason rear wings were on them was because of the diffuser interaction, the diffusers extended very high to generate huge downforce levels.
Also see the lmp's fr example, they all have raised footboxes to get a larger front diffuser, this small area can have enormous effect on the overall handling of the car, but this is pretty much irrelevant on the formula cars as these cars dont have understeering rpoblems.
The original idea of the raised nose was done by Tyrell to have the nose less influenced in the underbody airflow, the donwforce lsot by the higher nose was gained back double in the diffuser section, later on this idea got further developped with the front wing going under the nose to generate more front downforce, this was also develloped more and more with bigger planes under the nose until that was banned, now all the central downforce gneration is back tot the nose so they have different builds to meet their needs.
Most teams went for a semi height nose cone, and alot were really fat to get more downforce out of it i nthe excense of drag.
"Bite my shiny metal ass" - Bender