Sharing: can be a file in many folders? *
Yes by doing drag and drop
No if you move a file it will be only in the folder you have move your file to
Yes by doing CTRL+drag and drop or SHIFT+Z
What is the Drive storage limit? *
There is no limit you can store as many non native Google documents as you want
100 Gb. If users need more space they can ask the helpdesk to allow it
30 Gb. There are best practices in GOmmunity to avoid to reach this limit
Is it possible to share a drive structure and Google docs with non Solvay partners? *
No it’s technically not possible
Yes you can do it and there is a procedure to let your partner create a Google account and documentation available to teach him how to use Google Drive
Yes but you can do it only if your partner already has a Google account and it’s not recommended