Insert/update data into relational database tables only after administrator approval - how to approach it?
You basically have two options:


Extend each table with a 'Status' column, with possible values 'New', 'Approved' and 'Rejected'. Maybe another column for remarks by the administrator, and one to identify the owner of the record (which might already exist). All modules except for the import module should always filter on Status = Approved, which also influences your indices. This approach minimizes the impact on your data model, but that's probably the only advantage.
Build separate import_* tables for each table. They'll have the same structure as the tables in 1. Once a record is approved, it's copied over verbatim to the 'real' table. Creating and maintaining the tables is more work, but data is better separated and you don't need to change the logic of your core application.


There's no built-in waiting queue for INSERT statements in MySQL (or any database for that matter). What you describe is generally handled in application logic, and the database is just there for storage.