It depends on how you booked. If you booked through the cruise line they will come from them. Booking through a travel agent the line may send the documents to the office and forward to you.
As for delivery method it can come from a TA by postal mail, UPS, DHL or FedEx depending on the courier service they wish to conduct business with at the time.
Some cruise lines are sending documents via e-mail directly to the passengers and has to be printed out, referred to as E-DOCS.
If you do not get any documents within 10 days from sailing call the cruise line to verify all is well. The manifest will be there at check in, just have your booking number on hand. Fill out all the information on the cruise line web site for your cruise, that is pre board information.
Round trip Los Angeles to Hawaii, Summit March 26, 2006
Vancouver _ Alaska _ Los Angeles, Sept 16, 2006 on Summit