Hello, and thank you for your message
Overall, the project is documented at Growth/Positive reinforcement. The impact module is part of positive reinforcement tools, and, overall, it is part of the entire Growth features. Please don't forget that these features are for newcomers; we provide certain features for experienced users (such as mentorship) but the impact module is not one of them, even if it gains on popularity.
a) What do you mean by random? Only edits made at the main space (Articles) are taken into account. I checked your impact data on a few random days, and the numbers make sense. Again, it is not a feature for experienced users: we decided to highlight what matters: edit to the contents.
b) can you be more precise? Which page are you referring to? If it is Special:Impact, special pages don't have talk pages.
c) I tested the shortener on your impact module (Special:Impact/Stuartyeates) and https://w.wiki/873v sends me to your impact. https://w.wiki/873x goes to mine. However, if you don't add the username to the URL, you have the case you described. I documented it on T350932.
d) i) All impact is shown for articles.
d) ii) You'd like to have a comparison between the edits graph (in bars) and the views graph (the line)?
d) iii) We asked ourselves the question, and we were afraid of overcrowding the graphs with two sets of data at the same place. The distinction between the two graphs wasn't highlighted as an issue during the testing we performed with newcomers.
d) iv) I'm not sure to get it: the graph highlights pages views for everyone, not just the pages you visited.
e) Good idea, I documente it as T350936.
f) As I said, we have only take articles into account. Logged actions would be for a next iteration, for ex-newcomers looking for challenges. You mention barnstars: we have a few ideas around providing rewards to newcomers (and beyond), based on the number of edits.
g) The edit count is based on what we have in the database, i.e. what you have in Special:Contributions. Regarding pages views, we rely on stats.wikimedia.org.
Hope this helps, and thank you again for your feedback! :)