6a) Q: Does the information seem accurate? A: Strange, many of the browsers versions return same results. You have to look over all the information to get a full and accurate picture of the Browser version and the OS Version. But, overall, Yes, the information seems correct. Firefox is minimalist and good information.
6b) Q: Which properties are different? Which properties are the same? A: Same-ness: Browser Name is all the same - Netscape. Web Browser Version and User Agent give almost identical information for each browser. Since it is all on 1 Operating System, that is similiar but not totally the same, since Windows was originally built for 32 bit OS. But 64 bit applications are starting to be deployed ( Firefox ). Different: Firefox is 64 bit app, but all the others are a 32 bit app. Each browser reports the underlying HTML engine when you look closely, IE - Trident, Chrome and Edge - Apple Webkit, Firefox - Gecko. Also, when you look closely, you can see the browser version in the User Agent Information.
6c) Q: Explain the challenges using these properties. Which properties provide useful information? A: Web Browser Name is useless. Web browser version is almost useless, especially on Firefox, bummer. Operating System is OK, but this property really does not matter all that much. User agent is chock full of goodies. But it comes with a huge huge catch. The information is sprinkled all over the place on the different browsers. And the version information is all over the place. User agent is great, but you are going to have to have a huge amount of code for all the different versions of the browsers, all the different browsers. Augh! But such is the state of affairs with the web. Different browsers, different versions of the same browsers. Different points in time that each browser supported a different standard. That is the current state of affairs. And, basically will always the the current state of affairs. So, get used to it. Deal with it. Code to it. And move on. Just estimate the correct time and effort necessary to deal with these issues.