1. it`s due to the gravitational pull of earth which causes Moon to orbit the Earth.
2. No,it`s not always noticeable.You must have heard that earth pulls apple so it falls downward but the fact is apple also pulls earth but the pull isn`t noticeable.
3. I have only one thing that is the distance between the masses.
4. The quantity of matter contained in a body is called it`s mass whereas weight of an object is the force of attraction with which it is attracted towards the centre of a planet.Mass of an object is constant everywhere bt weight of an object varies from place to place.Mass is measured by beam balance whereas Weight is measured by spring balance.
5. You will fall back on the surface of earth.It happens because of the force of gravity of the earth.
6. If u jump on the moon u will float away(I guess).
7. Weightlessness is a condition where weight of an object is experienced to be zero.The mass doesn`t change as it remains constant everywhere.I will add an image for this one which may help you.