Magento定制xml结构的变化

I am new to Magento and what I am trying to produce is the following ( but I am unsure how to do this):

  1. How would I add new columns to the order page
  2. How could I integrate XML for sending order data to what ever the location is that I am sending it to.

I am unsure about the folder structure how to modify the files to produce the above. Do I do it via the lib hooks or other?

Were do I place the xml feed document etc