Answer to Question 1
Use the Ctrl / Option key to make the first copy, then enter 5x
Answer to Question 2
Assemblies that are created by copying 3D solid parts like these are static assemblies; that is, they do not change to reflect alterations in the individual parts.
Dynamic assembly, parts are imported into the assembly through a linking process that allows the software to update the assembly as individual part files are modified.
Dynamic assembly.