On your first point, as a non-expert in law and law history, I wonder to what extent these differences in trial procedure are rooted in the difference between common law and civil law.

To add to the examples, I'd say that France and Italy have procedures very similar to those described as the German system, and indeed all have a civil law system.

However, the link does not seem that obvious : the way trials are organized is not necessarily dependent on the way law is built.