Login to pervious version with Full Access account.
Export data and then import in to new version.
I think so, never try - I always set hidden option to import data as Admin.
I'd use a script in the new version that imports all records from each table of the old file into the new. If there are additional data manipulation needed to get the data properly configured in the new version, you can include script steps to do that as well.
No need to export when moving data from one file to another. You can also use the "matching names" import option to easily align most ields between the two tables in each import.