Okay the weapons being made when Jenova came has been established already in this thread. By Kishi and backed up by TLP. I myself remember the scene too.
The Northern Crater is enough evidence for me that she arrived on a meteor, it's certainly enough to establish that the planet would want to fight any threats BEFORE they hit it. The paintings in the Temple of the Ancients, and the sheer physics of creating that crater would back up the meteor theory.
For hopefully the last time. Holy and lifestream are part of the planet, they came from it, they have the same if not less power than the planet itself.
