The shore power cord should come with the unit, but the water and sewer hoses are not unless your dealer "gives" them to you as a starter kit. When we got our BH, I declined the "kit" since I had better hoses than they would have given me (from our TT), and didn't need the pack of toilet paper. The dealer should also install a single 12V battery in the rig, as well. If they do give you sewer hoses, you will probably want to replace them after the first season with sturdier ones. A bedspread and pillow shams should also be in it. From our experience, all of the necessary appliance manuals were included in the owner packet, a blue plastic attache pouch. Many other manuals or instruction sheets can be downloaded from the Tool section on this forum or by visiting the supplier's website.
Look carefully at the options available from Heartland before you order to decide whether or not you want them. Many things like slide toppers or windows awnings can be added later by the dealer, but dual pane windows (if available on Sundance) need to be added to the build order.