Just to keep you informed that I managed to import Customers, Items and Quotations from Odoo 9.
The problem with the status of the quotation always shown as 'Draft' instead of the imported value was fixed when I changed the default value to 'Open'. Don't ask me why, but at this state the current imported value is correctly displayed in Quotation List.
To change the default value of the Quotation's status, go to Setup -> Customize Form -> Quotation
At the bottom of the table, edit the line 'Status'.
In the field Display -> Default -> replace the value 'Draft' with 'Open' or any other value I think.
The Quotation element seems to have two values. Status (can be overrode during importation), and Docstatus (the value that erpnext is really using, apparently 'Draft' by default even after importation).
Do I need to post a bug report ?