you jump up high and float
Yes, you can fight gravity. We all do it everyday. You just cannot win when you fight gravity. Gravity will be there no matter how you fight it.
They are similar, in that one is the absence of the other. However, they are not opposites, so they could not be considered 'alike'.
The gravity on earth is 9.8m/s^2 I believe the gravity on the moon is 1.6m/s^2
Depends on the atmosphere. location, place, space and time of zero gravity