Currently the nodes don't support ByteStrings. You would need to change things in the code to be able to display them I think. What is your use case for ByteStrings?

I think something is wrong with the orientation of the corrdinate systems. They Best way for having everything well arranged is to use one of the existing working robots. Delete all the meshes out, move the pivots to the new axis positions and move the meshes in. Now use "Calc Kinematic Parameters". Also Elbow Setting needs to be as set to the correct value. By this you have the guarantee that the kinematic is ok. Or there is a Prefab "EmtpyRobotKinematic" which you can use for this.

I don't think that there is a way for doing this. It is also a little bit "against" the simulation logic. Markes can't be read from external devices in real systems. You could use S7 interface maybe instead.

Perfect - congratulations - in the end it looks like you did the interface pretty quickly.