Interstate Land Sales Full Disclosure Act Amendments of 1979 - Revises specified requirements concerning the sale or lease of lots located within a municipality or county under the Interstate Land Sales Full Disclosure Act. Requires that a title insurance binder or title opinion be presented to the purchaser prior to the time of closing. Exempts the following transactions from the terms of the Interstate Land Sales Full Disclosure Act: (1) sale or lease of real estate by a developer who is engaged in a sales operation which is intrastate in nature, and (2) the sale or lease of real estate by a developer who has fulfilled specified conditions to the resident of another State when the principal residence of the purchaser is within a radius of 100 miles from the property. Directs the Secretary of Housing and Urban Development to conduct all actions brought under the Interstate Land Sales Full Disclosure Act in accordance with the Administrative Procedure Act.