Not that I know of.
Yes: /content, /layouts, /themes, and config.toml. 
In all seriousness, I don’t know how to help you without looking at the templates, configuration, and at and least one example (including front matter) of each content type, even if contrived.
I don’t think so, but see the release notes.
You can search through this forum for words like “template” or “inconsistent” — perhaps you’ll find something that looks familiar. For example:
- https://discourse.gohugo.io/t/inconsistent-builds-with-hugo-help/19689
- https://discourse.gohugo.io/t/inconsistent-output-on-builds/12867
Finally, take a hard look at the difference between events and news. You have a similar quantity of each content type, so, all other things being equal, I would expect a similar number of failures. One obvious difference is the existence of .ics templates for events, but not for news, and I’m sure there are other differences as well.