Enstar will pipe gas to your home. You are responsible for plumbing gas to the appliances in your home. This will be easier, and more affordable, the closer your appliances are to each other and if the line can run under or outside your house (in a crawl space, for example). Installing appliances on second stories or where you have to run pipe through walls will be more expensive. All natural gas appliances have to be vented and many need to be placed on exterior walls for venting.
If your home is plumbed for propane it may still have to be re-plumbed for natural gas depending on the size and type of pipe used. Alaska state law does not prohibit you from pluming your own appliances, but Enstar will inspect the installation before they hook you up to natural gas. Tips on converting to natural gas from Enstar can be found here. Information on code requirements for our area can be found here.