National Electrical Code Articles and Information

1. [250.64(E)]. They have to be electrically continuous.
    

2. Table 250.66.
    

3. [250.68(B)]. An effective grounding path.
    

4. [250.70]. No, unless you use a clamp or fitting listed for use with multiple conductors.
    

5. [250, Part IV]. Generally, bond them. What you don't want to create is a difference of potential.