Generally, set-back thermostats do control AC as well as heat. When setting it up, you will set the schedule you wish to follow. If you decide to change it at a later date, they are very simple to update.
Yes. Setback or programmable thermostats can be programmed to control both heating and cooling. For more information please visit: http://www.energysavers.gov/your_home/space_heating_cooling/index.cfm/mytopic=1272