A. If you use a 5 degree setback you can save between 5-10% on your annual cost to run the furnace.  The cost to install a programmable varies greatly depending on what you purchase. It may take between 5-10 years or more to get a full payback. 

A. Typically 10-15 minutes in mild weather. The closer you get to the max design temperature in heating (0 Degrees) or cooling (90 Degrees) the longer the run cycle will be.