For 1), it could be that one set of engineers was tasked with gathering emissions data and finding which parameters got the legal result, another set wrote the software which gathered the data to determine the run profile, and another was tasked with setting the parameters in software for a given run profile. And, the internal emissions testers are probably told to replicate the various government trials. It could be probably done with just one or two directors knowing the whole story.

Reminds me of the denouement of "Real Genius": https://www.youtube.com/watch?v=HoT-h0S1gkE