Answer to Question 1
Answer: If only the radius of the Earth were doubled, you'd have one-quarter your weight. If only the mass of the Earth were doubled, you'd have twice your weight. Taken together, your weight would be half. The gravitational equation nicely guides this answer.
Answer to Question 2
Answer: The sum of a satellite's potential and kinetic energies remains constant if the satellite is in a closed orbit about a planet. As the satellite moves closer to the planet, it falls with gravity and gains speed. Potential energy decreases, kinetic energy correspondingly increases, and hence speed increases. As it moves farther from the planet, it moves against gravity, its kinetic energy decreases, and its potential energy increases. Its potential energy is greatest when the satellite is farthest from the planet, and least when it is closest to the planet.
Plnaet Earth
Tides on Earth
Ogburn's Processes of Social Change
Climate Change: Timescale decades to centuries
The Global Impact of Climate Change
Earth Atmosphere