Printful is completely white-label, meaning there is NO Printful branding anywhere on an order's packing slip. Packing slips include all the sending information, all of the products included in the package, and pricing information. If the order is split into two shipments (because some products are packaged differently), there will be a note on the packing slip. Retail prices may be displayed on the packing slip - find out more here.
The return address by default is our own, but it will be your address if you have indicated that you want your address to be shown. You can do that in your profile by going to Stores > Edit. While you're there, you can also add a customized message that will be printed on each packing slip, as well as upload a custom branding sticker. The image used for your branding sticker will also appear on your packing slip.
You can also include a personalized gift message on the packing slip when submitting a manual or API order by checking "This is a gift" on the review page. A packing slip with a gift message will still show all order prices.