I may be wrong but from what I’ve heard from some “small” content creator on YouTube the money from the sponsored talks in their video is a much bigger part of their income than money from youtube coming from the YouTube-selected ads that play before/during the video.
Also, this part do not give any money to YouTube and do not use/collect any data on you.
Probably not, this is Quebec. I’m in a french lab and everything is written in English. You don’t really have choice as you are collaborating internationally. Even if the lab is based/funded in France, not all of the people inside will be french. They plan to have scientific advisors that are not french according to the link.