To answer the question about the Riverside layout, it looked like this:
The dotted red line shows the original track and then the reconfiguration. IDK when this work was done but TREcup probably does because Dave raced there. So did I in an enduro kart but the work was done by that time, the mid 80's.
Karts and amatuear sports cars used the connector at T7 to what they called T7A and called the short course. Can Am, IROC, etc used the entire black line while NASCAR took the shortcut from T6 to T8.
I believe the long track was just over 2.5 miles but I'm not sure. There were many elevation changes notably where the red arrow is before T7 was a rise that made entering 7 blind until you were up to the crest of the rise. There was also a considerable rise going up into 6 which then became essentially an off camber turn when the course flattened out in the turn. It wasn't really but felt like it. The shortcut made that a lot easier for the big stock cars to make that turn.
And lastly, T9 was banked and a pretty good banking at that. However, IIRC, the racing line was not up on the bank much but pretty much tight around the inside stripe. And then drift out while those pitting would stay inside. That was a good pit entrance.