1) That's a lot of precursors. Many people want Sync functionality, which Google uses to track your browsing history. And most people don't go through the privacy settings.

2) We don't really know, Chrome is not open-source and it's hard to tell from network traffic, since nowadays pretty much every webpage loads something from a Google server in encrypted form anyways (and with those request, Google could send all kinds of data).

3) For Chromium (which's source code is basis for Google Chrome), this project tries to collect and fix all the privacy-infringing stuff: https://github.com/Eloston/ungoogled-chromium

4) There's many ways in which Chrome doesn't actively track you, but infringes on your privacy by just being terrible at protecting it from webpages' tracking. As in millions of lines of code, tens of thousands of design decisions, all made by the biggest tracking company on the planet. No journalist can report about all of these, but it'd be foolish to assume innocence until proven guilty.