North County Transportation District (NCTD)
(http://www.sdcommute.com) is the main bus service in the area.College Blvd., Mission Avenue, El Camino Real, Coast Highway, Vista Way, and Oceanside Blvd. are the major arteries in Oceanside, as well as I-5, CA-76, and CA-78.
You can walk anywhere downtown if arriving by train or bus. Many restaurants, a 16-plex movie theater, and the beach are within a few blocks.