Which light should be used for sunlight?

Good afternoon. I'm having some difficulty when working with lights and mostly the Z space. Maybe I could get some help here. I've posted a screenshot of the composition I'm working in. I'm trying to simulate the sun with lights from AE. My first question is: Which light should be used? Point, Spot, Parallel? WHich falloff option?I want the mushrooms to cast shadows on the floor. I tried using parallel light. Assuming the sun is in the further than everything (except for the sky), the shadows should be pointing to the screen, right? I can't get to make the shadows on this position. Each mushroom is a different layer, with different Z values. How should I position the light to make the mushrooms cast their shadows in the right position? Another question I have is about the ground. How should I position it in Z space? Part of it should be closer tran the mushrooms and some should be further. Should I split the floor in several layers and place them with different Z values? The sky, clouds, stones, trees, ground and mushrooms are all isolated.

Thanks a lot for the support and forgive me if my English isn't clear or good, I'm from Brazil.