iMovie libraries - Best practices, Dividing existing libraries, original clip location

What do you recommend as best practices for iMovie library and video file management?

To-date I have been creating a library based on events/clips in a single calendar year, but recently as I was moving libraries to a different storage location, the size of some years is large and unwieldy (> 200GB). I thought more about creating a library for each specific event so that library file size is reasonable and perhaps locating specific clips would be 'easier'.

My understanding that once a clip is imported into a library it is copied to the library file package and can be accessed as needed. I am wondering if keeping the redundant original movie clip file separately is useful or not.

Questions:

1) How do you structure your iMovie libraries? What are your best practices which you can share?

2) Do you keep the original movie files separate from the iMovie library package files?

3) If I have a 200GB+ iMovie library, is there an easy way to divide it into smaller libraries other than copy and delete events from the duplicate library file?

Thanks in advance for your replies!

Shoes