Answer to Question 1
The largest energy consuming appliance in the home is the HVAC system, and most of these systems are estimated to have a 30 loss of efficiency due to improper air side design and instillation.
Answer to Question 2
Both are measures of rate for air flow
FPM measures the rate of air velocity, in other words, how fast the air is moving. CFM measures the rate of air volume, in other words, how much is moving per minute