Yes, that vehicle power cable is included with the nuvi 2557LMT. The following accessories are included:
-Lifetime traffic antenna/vehicle power cable
-Vehicle suction cup mount
-USB cable
-Quick start manual

Yes, the nuvi 2557LMT will support entering an intersection without the city. It will prompt you for the state, the first street and then second (intersecting) street.

To save an address or location to your favorites on a nuvi 2557LMT:
1.) Search for an address or a point of interest (POI) using the options available in the Where To? menu
2.) When the address or POI is displayed on the map, touch the info button (center "i" button)
3.) Touch the menu button (three horizontal lines)
4.) Touch Save
5.) Enter a name for the location (if prompted)
6.) Touch Done (if prompted)
7.) Touch OK when notified that the address has been saved

The saved address will now display in the nuvi's Favorites/Saved menu.

To delete a favorite or saved location:
1.) Touch Where To?
2.) Touch Favorites or Saved
3.) Locate and touch the favorite you would like to delete
4.) Touch the Info button (center "i" button)
5.) Touch the menu button (three lines) in the upper-left of the screen
6.) Touch Delete
7.) Touch Yes

The selected favorite will be deleted.