HORTON CENTER: Horton Insurance Agency, Inc., Orland Park, will occupy the top floor of the Horton Center, a two-story office building and shopping center complex under construction at 144th street and John Humphrey drive, Orland Park.The 12,000-square-foot office building is scheduled for completion in early 1987. Completion of the 24,000-square-foot retail shopping portion of the project is slated for later in the year. D.E. O’Malley, Ltd., will be the leasing agent for the first floor of office space and for all of the retail space.