/3/ - 3DCG

I'll try to make it short since this board is slow af. My question is regarding posing of characters.

SITUATION:
I'm a beginner and slowly putting my workflow together. Modeling/retopo/UV/baking/texturing etc. However I'm sort of unclear about certain aspects of posing my work.

QUESTION:
1) If I have a finished in-game model including all maps/textures etc. Can I still pose it in ZBrush? Or would you recommend a better program for that purpose? I haven't really looked into it yet, but so far I just posed my base models by masking and deforming with the 3D gizmo, which isn't really professional. Is there an easy way to create basic rigs or is there no way around weight painting/rigging?

2) I don't fully understand how certain parts can be omitted from movement. For example if you have a knight with shoulder plates, how do you keep the shoulder blades as a hard surface without deformation? Do you just weight-paint around the plate?

Or if you want to move the finders on a robot hand, how do you make it so only the separate sections of the finger move in a 90° angle, without deforming the fingers themselves?

Pic related to show the type of construction I mean. On an organic hand, the skin surrounding the joint would move, but on a robot hand, the two 'bones' would basically move without and deformation to the topology. How is that working in CG ?

Would greatly appreciate any input or links to tutorials. Thanks.