Nice. I've wanted to do something like this, as I have a theory about the car pool lanes being worse for traffic. When traffic is bad, car pool lanes are just as backed up typically.
When someone wants to get in the car pool lane upon entering the highway, they tend to do so fairly quickly. This can cause a shockwave as someone flies from one side of the highway to the other. The same thing can happen in the opposite direction when a carpool lane driver needs to get off, and this issue is compounded even more since you can't always (legally) exit the carpool lane.
So I thought it'd be interesting to play with a simulator like this, add/remove carpool lanes, or lanes altogether, and see what results.
In the uncounted thousands of hours of driving on the freeway in my life thus far, I've observed:
* Drivers will improperly idle in a lane they feel safe in, refusing to keep right except to pass (this is actually state law where I live).
* Any deviation from a straight, flat, roadway (corners, hills, dips, anything) will cause the flow to slow; even when you can proxy the status of the roadway in front by the tail-lights of all the lanes of cars who /can/ see.
* Apparently no 'big' city anywhere balances jobs and housing. Cities too small to balance anything are also generally too small to notice the issue. (I say this because it seems like everyone is economically incentivized to drive as far as they can possibly stand from work for the cheapest housing; clearly there isn't enough housing near jobs to keep those costs competitively low.)
On your first point, that's the norm in my driving (most of both US coasts.) I've sometimes wondered what the saturation level is where the left lane should just be another lane to increase steady state flow rate. I guess it's when the lane becomes too crowded to cycle properly.
On your second point, I've always just assumed that that was a tall car thing because I figured they probably get more uncomfortable cornering. The same way I probably seem irrational when I speed around pickup trucks: they probably fail to recognize that their driving in front of me is like putting a wall in my face (and unlike semi trucks the drivers are no better than the rest of the people on the road.)
On your third point, the US has baked in too many policies that are prohibitive to sensible development patterns. The implicit subsidies for low density living and the federally insured mortgage cone to mind as two of the worst.
When someone wants to get in the car pool lane upon entering the highway, they tend to do so fairly quickly. This can cause a shockwave as someone flies from one side of the highway to the other. The same thing can happen in the opposite direction when a carpool lane driver needs to get off, and this issue is compounded even more since you can't always (legally) exit the carpool lane.
So I thought it'd be interesting to play with a simulator like this, add/remove carpool lanes, or lanes altogether, and see what results.