The link I posted specifically answers your question about "which tables are linked to the customers table".
The correct way to upgrade your database structure is to use the supplied upgrade script. It takes all of 5-10 minutes. Maybe 15 including backups.
The documented upgrade instructions are written and supplied not just to take up disk space, but to provide a plan which will prevent you from having the problems you're reporting.
So, since it seems you are bent on using a new database and merging data, instead of upgrading the original one, you'll need to:
1. Upgrade your "old" database using the supplied zc_install upgrade script.
2. Then import the tables related to customer-data.
That way you'll have the data in the right format.




