Generating Order History CSV

I am currently working on an order history export to CSV for a client. They would like to export two reports — same data, different sorting. One will be sorted by user and one sorted by product category, then sub-category.

Being new to woocommerce, I was wondering if there is any easy way to get this data. I have a submenu page in the admin which the user can select filters, which will send $_GET variables to the export script.

What is the standard way of retrieving order data ( date, status, order_id, name, etc )?