Hi,
For the first question, you have to make sure, that the exported VQL file contains everything that is needed to create all elements in the Virtual DataPort Server. You can do this by opening the VQL file in a text editor and check if all elements are included, especially the ones that threw an error.
Regarding the second question, it is possible to export and afterward import just one database. You can go to File -> Export database in the Virtual DataPort Administration Tool to export one specific database.
For the backup of the server you have to export the whole server under File -> Export ... I recommend you this two articles in our documentation for detailed instructions on this topic:
[Exporting the Server Metadata](https://community.denodo.com/docs/html/browse/6.0/vdp/administration/exporting_and_importing_the_server_metadata/exporting_the_server_metadata/exporting_the_server_metadata)
[Importing Metadata Into a Server](https://community.denodo.com/docs/html/browse/6.0/vdp/administration/exporting_and_importing_the_server_metadata/importing_metadata_into_a_server/importing_metadata_into_a_server)
Hope this helps!