Hi,
If the CSV file is not easily opened with Excel, that's because of the CSV separator chosen in the Files section of the Hikashop configuration. Change it to the one your Excel prefers and that's it.
Also, if you want to only have the columns you want, you can create a mass action of the type "order" via the menu System>Mass actions with an action "export CSV file". You'll be able to choose the columns you want, and add a filter on the order_created or order_invoice_created column of the orders and then click on the "proceed" button to get the CSV file.