DRTV generally bypasses traditional retail stores to make a product sale directly with the consumer, but can also be used to drive product sales at retail. DRTV is comprised of three primary marketing subgroups of short form, long form and live home shopping.
Persia/Persian is more or less synonymous with Iran/Iranian. Persia is just the older name whereas Iran is the country's modern name. I think people from Iran call themselves Persian because of Iran's negative image in the west since the 1979 revolution.
The language is called Farsi, but many people say Persian to help others understand what they mean when they say I speak Farsi.. It's probably better to say Farsi rather than Persian, but Iranians will understand both. People from Iran are called either Iranians or Persians.