Multiple character parts can be done using MasterPoseComponent. That will require the partial bone hierarchical to be same, but if you have all body parts, it will follow what master does.
For master/slave, you can use blendshapes. You can use blendshapes for all animations. Make sure you enable “Import Morphtarget” when you import the mesh. The name of Morphtarget should match with name of BlendShape Curves.
Facial animations are a bit different topic. You can do this using just animation (scaled animation) or blendshapes - FBX Animation Pipeline in Unreal Engine | Unreal Engine 5.1 Documentation -.
We have a couple of third party who are working on facial capture system, so those plugins will be coming.
Thanks,
–Lina,