I have a client that lost his Zen Cart developer mid-project. I am an experienced PHP developer, but new to the cart.

The requirement is to add four new fields to the Client Details, the page you fill out to get an id to the site. He wants to add a Fed Tax Id, Business Type, etc.

Going through the forum and faqs, I think my approach is to:
Add a new database table for the fields, this will prevent me from losing the fields when he upgrades.

Add the fields to a language file in the language override directory. This file already exists, it was left by the previous dev.

Add the fields to a template in the override dir. Like the language, this file is already there, it just needs the new fields.

Change the code that saves the data (header_php.php?). My understanding is that this is outside the override system. I believe I need to back up the original, make the changes, and backup the new. Lastly leave good notes about this so that I will remember to deal with it when we upgrade in the future.

If I am about to blow a big hole in my foot, please let me know.

Thanks!