Help with Sensory Physiology !! (action potentials, temp and food) !!!

1)An action potential is an all-or-none event, meaning that the amplitude is always the same, regardless of
the characteristics of the stimulus. If action potentials are the only information that the brain receives from
sensory neurons, how then is the brain able to perceive each of the following?
a) Changes in the intensity of a stimulus?
b) Change in the duration of a stimulus?
c) The location or specific modality (type) of stimulus?

2)Temperature receptors are scattered throughout the body. Between 20oC and 40oC they adapt slowly, and
eventually stop firing action potentials. They do not adapt at temperatures below 20oC and above 40oC. In
other words at those extremes of temperature they continue to fire action potentials which reach the brain.
How does this have survival value for an animal or a person?

3)Why are mint flavored foods containing menthol perceived as cold, and foods containing the chemical
capsaicin (the active ingredient in hot peppers), perceived as hot?