Problem is if social media is being used to stay in contact with friends / family then you are stuck with where they are, as they generally don’t move to a new network with you. If it is for news etc, I actually prefer a good selection of RSS feeds that I follow in my RSS reader.
I’m on lots of different social networks for blogging and although MeWe has my far biggest followings, it is centralised and non-FOSS - it’s the site I’ve also had the most troll issues on. The Fediverse (numerous site services to choose from) has the most potential, being open and federated widely.
Could be yes - although I seem to think with my transfer from one Samsung to another it brought the files and settings over. Can’t remember for sure now as was over a year ago, but I did not recall any major issue.