Background: We live on a large mountain. And the soil we have here is full of small, medium and large rocks everywhere. Throughout the time we've lived here, growing trees is really hit and miss. Due to our ignorance of planting trees and types of soil to use.

I know now that specific trees require specific elements (nitrogen) and a specific pH level in the soil in order to thrive. 

1. Should I remove S/M/L rocks from the existing soil before planting new fruit trees?
2. Should you ever use top soil when planting new trees when replacing existing soil?
3. If not (2), then what type of soil is recommended for planting fruit trees?
4. How often should someone water fruit trees?
5. Is there a general understanding of the elements needed for planting fruit trees, and the pH level in the soil?