Should be Simple, but Mind Boggling Math regarding Vector3/Quaternions.

I'm currently screwing around in 2.5d environment that uses mostly x and z coordinates.
I have a character whose ability on use instanciates prefabs around its target. Like in the figure below.
In blizzard's, galaxy and world editor something like this was incredibly easy. But I have not a clue how to do this in unity.

How would I get the new positions of the instanciated prefabs.
How do I offset a position by a certain angle in Unity?


EDIT: uh... I just decided to use vectors with x and z coordinates and old school math. Im good.