Regarding traffic counts at an intersection, good luck. The City of Denver might, maybe, have traffic counts. Of course Apple, Google, Microsoft, and others have a good idea of traffic patterns around almost any/every US city, but I am not even sure if you can pay for that information. It surely isn't free.
On the demographics and similar information, the Census Bureau American Community Survey (ACS) might get you in the ballpark for free: Access American Community Survey (ACS) Block Group Data. If you are willing to pay, that opens the doors to many other options. Esri Business Analyst would likely give you some good information, and Esri Demographics is another Esri-integrated option. There are numerous companies outside of Esri as well that package/bundle and sell this type of information.
