Hughes Gearing For July ILandmark Debut\ target date of July 1 has been set for opening the Landmark Tower, according to gambling license applications filed yesterday in Carson City by representatives of Howard Hughes.Hotel Properties. Inc., a wholly owned corporation of the Sands Hotel, also owned by Hughes, filed license applications for the Landmark with the Nevada Gaming Commission.Hughes representatives cautioned, however, the July 1 target date hinged on many factors including the hiring of more than 1,000 employes for the new(See LANDMARK, Page 1)