1. I guess nothing is certain - but even if they are a complete hoax they still can't correlate searches with my other data (mobile, mail, documents, http heade

1. I guess nothing is certain - but even if they are a complete hoax they still can't correlate searches with my other data (mobile, mail, documents, http header data from javascript api calls on basically every site I visit, ....). This correlation is something other search engines explicitly state that they will do. 2. You don't know that.