Best route for DTV is to use an outside antenna. Lots of information at the antennasdirect website.
Don't get suckered by the "digital" splashed on ads or cartons, the old style antenna works just fine with digital TVs. The antenna only captures the signal and doesn't care if it is analog, ham, or digital, it is the receiver's job to take what it needs.
I am approx. 45 miles from station towers to the east and west, an old style antenna in the attic works just fine with a signal splitter to various rooms. That said, the signal is line-of-sight so what you do will depend on your location. Your antenna needs to be high enough to receive over the nearby hills and neighboring buildings.
I don't think so. They work well even without any antenna.
You will need antenna to catch digital signals. other wise you will not able to get good picture quality.