E.s.e. I you move files using Tonfotos (like Control+M for example), then it will keep all the faces. However, if you move outside Tonfotos, such as using File Explorer, then for Tonfotos it will like old file was removed and new file appeared. Faces will not be assigned by default, you will have to confirm people again on that photo.
As to backup, the most precious thing is you photos. So there is no debate about that, you have to think about regular backups. Otherwise you may end up losing it, either by hardware failure, or by human mistake. So A is mandatory.
B is optional, it will help you to avoid several hours of scanning in case our OS crash or application failure.