Difference in methods of modeling connectors

Hello, I wonder if the different fastener connector realization types can be created manually by the use of constrained nodal rigid body elements?

I am working with LS-DYNA interface, I wonder what the difference is between bolt(CBAR) and bolt(general) described in https://2023.help.altair.com/2023/hwdesktop/hwx/topics/pre_processing/connectors/realizations/bolt_general_c.htm?

I want to model a threaded insert that is inserted into a solid part, what is the best approach for doing that? Is there a specific fastener connector type that is recommended that includes the connections inside the hole created by the threads? Or should you model the insert as a solid cylinder and use a "spider" element on top of it as in the figure below? 

What is the difference between modeling a bolt that is not threaded and modeling a threaded screw/insert when it comes to the type of fastener connector that is appropriate? How can you manually model the connections for a threaded screw/insert?

Is the connector type below only appropriate for shells and for modeling bolts? Can it be used for modeling threaded screws/inserts as well or not?

Finally, are RBE2 elements the same as constrained nodal rigid body elements in LS-DYNA?

Thank you in advance!