Hi James,
1. The "New Arrivals" sort option will list the Products in ascending order by the Created Date of the Product. The ability to display Products that are only less than 1 month old is not currently supported in the BuyNow module but you can use the Featured Products module's "Show New Releases" feature which will display products 30 days from the product create date.
2. Yes, you can allow registered users to print out invoice for the customer pick up in store. For more info, please see Pg.221 in the SmithCart Manual at the following link -
http://www.smith-consulting.com/Porta...
Hope this helps!