Tennis balls contract when heated which means that it will bounce higher.
The air inside the ball expands on heating and this, in turn, makes the ball harder / more elastic.
A heated tennis ball bounces higher because the hot air inside the ball is lighter than the air around the ball therefore giving the tennis ball the ability to bounce higher.
That depends on the material from which the ball is made, if this material is elastic then no.
If the weather is cold the ball may harden and become stiff, this makes the ball have less pop and results in a slower playing ball. If the weather is warm then the ball will become more elastic and bounce higher. If the ball is sat outside for extended periods of time the constant cooling and warming of the ball will cause the rubber to lose its form and become flat with no bounce.
The heated, then the room temperature, then the frozen ball. It's the heated because of how fast the molecules are moving. :)
If the ball has a dent in it and you heat the ball in hot water it will come back to its original shape.
Because the internal pressure increases when the air in the ball is heated and this increases its 'bounceability'. If the ball is cooled it's like partially deflating it.