This movement is called convection. It can be found in liquids, gasses and rheids - solids that can also experience movement ( on a big time scale), such as the earth mantle. One of the types of convection is diffusion: net movement of gasses from higher to lower concentration areas.
No, this is statement is false!
An absolute age is not dependent on anything - it's the age in "years" not "older than" or "younger than".
The position of rocks is more inherent to the relative age of the rocks- relative to the other layers of the rocks.
Igeneous intrustions are created when magma that is trying to get out from under the earth, cools before it reaches the surface and causes geological irregularities. there are 3 types of igeneous intrusions: sills, batholiths, and dykes.