I've seen very few RVs with a factory installed water filter.
They should all come with a power cord, because most RVs have the power cord permanently attached. Some have a removable cord, and that should be included.
Batteries and Propane tanks should be included as well. Some dealers might charge $$ for batteries, but all dealers I have been to (10+) include batteries, propane tanks, AND they fill the tanks.
Don't expect much more than the above to be included.
Some dealers throw in a "starter kit" which is a box with a cheap sewer hose, a fresh water hose, black tank chemical pack, maybe a water pressure regulator and a few more trinkets.
Other dealers might give you a $50 gift certificate to spend in their parts dept, so you can buy what you want
