Not sure about threats, but I've seen plenty of fake news, conspiracies, etc; many of which have been tied to Russian disinformation groups (or other malignant foreign interests). See the Nation in Distress group; https://www.washingtonpost.com/technology/2018/10/11/faceboo....
Of course. All it requires is some naive (usually older) family members. In this case, my in-laws are in their 70s, and extremely right-wing. They would share stuff from the Nation in Distress group all the time before Facebook banned it. That is just one example; Facebook has been extremely instrumental in providing a platform for disinformation and propaganda. Just because you don't see it in your own bubble, does not mean it is not a threat.