Product import automation

Hello,
I love zen cart, I've been using easy populate for a while.

Where would I go about getting the database updated automatically? What is the best practice? Is it best to do it from the command line and through sql? Or should it be done through zen cart somehow?
Is it best to write a php script and have a cron job that calls the php file every 6 hours?

Or is there some way to automatically run easy populate, or call it from a cron job?

My inventory changes daily, the distributor offers a "live" download of which ever products / columns I need based on a URL. I can get the product codes, prices and quantities and more in a csv or xml file.

I would like to automatically grab this file and insert it into the zen cart db.

Any tips on where to get started writing a script like this?