The Geometry Nodes modifier for generating the electric joints arcs has multiple properties to adjust the look. One of it is the amount of electric arcs to display in viewport and render mode. For the generated electric arcs are real mesh it's a pretty heavy load for the armature to handle in the viewport in real time. So the amount of arcs can be set for viewport and render mode separated.

The character includes a main body, with a wooden look, spotted with bloody human flesh / skin, the limbs are connected with electric joints (geometry nodes modifier), the metal plates, connected to the body. All separated main objects with separated mesh islands.

Yes, of course. The electric joints are separated objects with can be deleted and replaced with you own objects and materials. But keep in mind, that you have to apply / parent those objects to the armature.

For the body, metal parts and electric joints are separated objects with separated mesh island each. You can change and apply different materials to smaller and bigger parts. But also the materials, which comes with this character (wood, metal, human skin, etc.) is a separated procedural material combined with 2k textures and spot mask for blending. You can highly adjust the wood, or apply your own material as wood, the human skin, the metal, etc.