My Errors found.
1: ElectricItem.manager.use() has a buildin chargeFromArmor call. So useless.
2: You spawn the Entity on the client side so it has on servers no effect.
My answers to your question:
1: Custom IItemRender class with the draw call. From what i know Quantum Pack (the version i link to in my version) has a OpenSource renderer. That didnt change between 1.6.4 to 1.7.10
2: Check my found errors.
3: i think there is a function called canBeColided with or something. But that removes all Interaction code from other entities so you have to do that yourself then.
4: read 3.