Answer to Question 1
Answer: Objects not only radiate energy they also absorb energy. If an object radiates more energy than it absorbs, it gets cooler. If an object absorbs more energy than it radiates, it gets warmer.
Answer to Question 2
Answer: The air pressure at higher altitudes is less than at the surface. It takes time for your body to adjust to this new pressure, so the air inside your inner ear pushes outward more than the atmosphere pushes inward, giving you that popping feeling.