AMHERST, Mass - Homecoming Festival ''99 at the University of Massachusetts, Sept. 30-Oct. 2, will mark the 125th anniversary of the UMass Alumni Association and feature campus-wide events. Chancellor David K. Scott will award the Chancellor''s Medal to 10 distinguished faculty and alumni during a convocation Thurs. Sept. 30. The traditional Homecoming parade prior to the football game against Hofstra University takes place Sat. Oct. 2, and tours, concerts, and reunions are planned throughout the festival. Other events are the second annual "Eat and Run" mini-conference; The Big Lunch, a campus-wide community event; the 25th Annual Multibands Pops concert; and Homecoming Park at the football stadium, a celebration that includes games, music, and food, along with special reunion celebrations. Many events are open to the public. The following is a partial schedule of events for Homecoming Festival ''99.