I’ve managed to somehow fracture one of my libraries so that actors in movies added recently are not affiliated with the same actor in movies added a long time ago. So when I go and search based on an actor, I only get some of the movies the actor is in, not all of them.
Probably not, because it will only read the file header with the metadata. At least that is how it works on regular, locally attached storage or with LAN file shares.
Whether it works that way with cloud storage depends on how smart the software is which mounts the cloud storage.