When I set the thermostat to X degrees, is that the temperature at which air is pushed out through the vents?
The Thermostat temperature is of the room, at the thermostat. The thermostat has a differential of about 1 or so degrees. Meaning if it is set for 70 deg, it will kick on @ 69 degs., then off @ 70 deg. The actual temperature of the ducts will be something different.

EDIT:
The question is about AC so it is ductwork. Each register is likely to be at a somewhat different temperature &amp; CFM due to duct length, size, how many turns, etc. This is often measured with an anemometer.