Google analytics is ubiquitous and you're tracked to your bones especially if you're logged into your Google account and while they don't read your Gmail email content, they put you in the social graph according to any email address or URL in your email and they have better idea about your past more than you do.
I still use Google search as there aren't better alternatives but I never use Gmail nor Chrome as I have plenty of alternatives for those.
Depends on what you mean by "read". Google (and MS, and likely others) certainly parse the content. For example pulling out times for upcoming flights you've booked without you needing to click into the email.
Obviously I have no way to know if they actually do anything else internally with the result of parsing. I have to assume that they do though.