There is no unit of "gravity". Gravity is described in terms of its effects,

namely acceleration and force.

SI unit of force: [ newton ] = 1 kilogram-meter/second2

SI unit of acceleration: meter/second2

Yes. And the local force of gravity.

1 cubic meter = 1000 liters. It doesn't matter what you are measuring.

There is less gravity on the Moon. Gravitational potential energy can be calculated by multiplying weight x height, or the equivalent mass x gravity x height.

In other you mean, and yes. There is gravity every nano meter of the whole universe, nothing is away from gravity, gravity is everywhere.