Q:

Which theory is stronger, that iron came from outside or was formed within earth?

Where is the current body of science learning towards, that iron came from meteor or it was somehow formed on earth?

A:

The only elements that were formed on Earth are those produced by radioactive decay. There are four natural decay chains that start with transuranic elements and none terminate in iron; neither do the decay chains that are artificial or those that result from cosmic radiation. So all of our iron is from the Earth's formation or meteor impacts since then.

A:

All the material that eventually formed our solar system is essentially recycled star dust.   All iron on Earth was produced by large stars that existed before our Sun formed: the iron was created during nuclear fusion and later released when the parent star(s) exploded, presumably supernova.  After our solar nebula had formed and material had been gravitationally compacted, dense elements like iron did not get far from the center of the nebula before "precipitating" out into planets and meteors.  Thus the inner solar system has a high abundance of iron. This is in contrast to low-density elements/molecules that were in general able to escape the center of the nebula and make it pretty far before being pulled into a large mass.  So we have high iron planets and meteors close to the sun (relatively speaking), and very little iron in the "gas giants" part of the solar system.  I would consider this to be material that is "already there" but certainly some iron has been added by meteors.

A:

I believe the element iron (Fe) is formed by stellar nucleosynthesis.
stellar nucleosynthesis:
it's a process of continuous fusion of the star element to reach heavier and heavier elements. starting from hydrogen (H) till iron (Fe) (the heaviest element the process could reach). 
Each 2 atoms of light elements fuse together to form heavier element atom. 
For example 2 hydrogen atoms (H --> 1 proton) fuse to form helium (He --> 2 protons). 

