I’m guessing that parenting to both the metarig and the rig over constrains the bones much like the ik/fk switching. Essentially two things are fighting over who controls the bones and the first paired item wins. Try unparenting the metarig and see if that works.
I really dont know what your expecting with assigning empty groups with the clothing, yes you are creating vertex groups for each bone, but they are empty and need to be painted in as there is no deformation data there
As for the metarig, its a basic fk rig, things like moving the legs for walking are going to be a bit of a pain as adjusting the whole chain to get a foot to plant on the ground is cumbersome, but there is an auto ik feature that can compensate. the only real thing youre missing out is the tweak bones for smears.
