Hi,

For upgrading the odoo community instance to the enterprise edition, you have to get the enterprise license from odoo and do the following steps.

1. Add the enterprise code in addons path

2. And install web_enterprise module. Make sure database backup has taken before doing this.

See:-  How To Upgrade Odoo Community Database Into Enterprise Edition

To activate full accounting in the odoo community edition, see this: How To Enable Full Accounting Feature In Odoo Community Edition

Module: Odoo 13 Accounting

Thanks

Hi Mattia,

1. It depends what you mean by 'full accounting'. Up to version 13, it's possible to do all your accounting in Odoo, just activate the 'show full accounting options' on a user through developer mode. The community module is however lacking the reports. You can add reports with OCA-modules (odoocommunity.org). 

2. Yes, that's possible. You can purchase a license and when installing an enterprise module you'll be notified where and how to register your database. 

3. Search the Odoo documentation on this, or go to subpage /web/database/manager. You can backup your database with or without filestore.

4. Depends on the data and how skilled you are with spreadsheets, but in most cases, you can do the import yourself.