Reference checkout documentation - tracking information syntax

Hello,

I am  working on building a custom analytics tracking module for reference checkout 2.03.0. Looking at the provided Google analytics module, I see code like this:

                    var shipping_address = order.get('addresses').get(order.get('shipaddress'))
                    ,    transaction_id = order.get('confirmation').confirmationnumber
                    ,    order_summary = order.get('summary')

But the commerce API documentation talks about  order methods that are more like order.getFieldValues('fieldname').  Can anyone point me to where the this stuff is actually documented? Specifically, I'm trying to get the customer  internal ID  and their email address.

Thanks,
David