File shares, previous versions, shadow copy

Hi there,

Sorry for my bad english.

I'm looking for informations about this function.

I have a windows server 2016 file server, with a specific drive for storing datas (say d:) and a specific drive for storing previous versions of files (say z:).

I can't find anywhere technical information about this, my questions are :

1. When I put a file on data d:, and the "previous version" schedule run, does this copy the entire content of this new file to z: ?
2. If yes, does this get compressed ? Because I did some tests on empty drives, and say with 6GB on data disk d:, I get approx 2GB of disk usage on z:
3. If I select no limit for drive usage for previous versions, how is working the cleanup process when z: gets full ? Older snapshots are removed ?

Thanks for infos