Thanks for your reply. I'm sorry you didn't find my code helpful; I enjoyed writing it, which I think is the main thing for volunteer work and I'll leave it up in case somebody else finds it helpful.
Here's some quick answers to your questions below, although some of them require more thought:
1. There's a lot of weird terms in Moodle already (CBM, SCORM, LTI) so I think it's good that we're trying to avoid more complexity and the work to hide advanced settings in recent versions of Moodle are much appreciated. Certainly the word 'Tin Can' shouldn't be visible to learners but we do need to mark settings relating to Tin Can as such. I'd ideally like to do all the Tin Can stuff as plugins, which means it'll only appear to organisations using those plugins.
2. This is one that needs more thought on a per module basis. I've outlined my suggestions for the quiz module above, but they need more detail. This detail is likely to be the focus of the next piece of work I do on this. I don't intend to tackle other modules at this stage.
3. I think following the standard should be sufficient here. the key thing is the next question.
4. I'm not aware of other LMS adding Tin Can tracking to their quiz modules. I'll ask around though. This is an opportunity for Moodle to take the lead.
5. Again, this one needs more investigation. I suspect the difference is that there are more Moodle events than we want to track and that we'd like to put more information in the Tin Can statements. it may be that we can trigger statements from events and then get the remaining info. Any input on this question is much appreciated.