Now, for a situation where I'd be driving about 30 miles/day with 1 passenger average weight, no load in trunck. Summer temperature, highway type driving.
How would I read the sticker? stay with 32psi?
Tire pressures are set by the factory to cover the load rating of the tire. Notice on the above sticker as the weight exceeds a certain limit they recommend that you increase the inflation pressure. The manufacturer of the tire will give the company a recommended range of pressures. Mazda then picks the pressure that it feels is the best compromise between the load rating and comfort.
If you want crisper handling and you're will to sacrifice a little ride comfort, up the pressure a few pounds at a time until you get the feel you like. I would not recommend dropping below the recommended pressure.
As an example, the Miata has a factory recommended pressure of 26 psi, which is fine for normal highway driving, but for twisty back roads most people up the pressure to 28-32 depending on the tire.
Don't forget, tire pressure should be check when tires are cold. Not after you just drove your car.
Tire pressure increases with tire temperature, and tire temperature increases with car speed. And the relation is not linear neither, more like expodential. If you visit michelin.com they give an example that a tire going at 160 km/h and at 190 km/h there would be a 3 psi increase. So never put the maximun pressure rating if you are going to do excessive speed. Personaly I follow the recommended pressure which is 32 for the 6.
If MPG is your goal, then higher pressure. Higher pressure will reduce the contact patch of the tire lowering rolling resistance.
But higher pressure will also increase the spring rate of the tire (yes, a tire is a spring) giving you a harsher ride.
Higher pressure reducing the conatct patch can also affect braking distance. Less tire contact with the road, longer braking distance.
Higher pressure can increase the handeling of the car. With higher pressure the tire will be less prone to roll over onto the sidewall during cornering, keeping more of contact path and increasing grip and turn-in responce.