Hello Guillermo
Here is a pong game I made a while back:
Pong.capx
This .capx should help you with some of your questions. It comes with a AI (Artificial Intelligence). You can adjust the AI speed to make it easier, or harder to play by looking for were it says "lerp(Paddle_AI.Y, Puck.Y,0.05)", and changing the speed "0.05" to a higher or lower number. You can also adjust the ball speed, and acceleration in the layout properties window. Also look through the events sheet to see how you can set the ball to start at random angles to give your game a more real feel.
I didn't comment the event sheet because I'm lazy, and it is pretty small. So if you have any questions about it just ask.
I hope this helps.