Hello There
1. Speed is the distance covered by a moving object per unit of time. It is simply how fast an object is moving without regards to direction. Acceleration is another concept which is rate of change of speed, specifically its velocity.
2. When you're on the earth, you are constantly being compressed between the Earth's gravitational pull and the Normal reaction provided by the ground.
3. Weight is a measure of the force of gravity on an object. Mass is the measurement of how much matter is in an object