soil test depth for orchard

I have cleared a small area of 0.6 acres to plant an orchard on.  It was full of small trees and lots of vines and is now cleared. It is on a slight slope where my neighbors get all my precious rain water.
The soil is mostly covered with woodchips and piles of branches.

I want to put down mostly Asian Persimmon (astringent and non) and Pawpaw.  Will be getting the seedlings in February and will graft the cultivars in the next few years.

In the mean time I want to prepare the soil in each tree planting hole before the seedlings arrive.  Does this sound like a good plan?

1) before anything goes down I will do a rough contour of the land and put in some swales and berms to direct the water to low spots and hold it there.

2) Then is the soil sample test.  Is 6 inches the depth recommended for fruit trees?  Logan labs will be the lab of choice this time.

3) Since I have a lot of clay just under a few inches of soil I want to use a post hole digger so I can add expanded shale and some gypsum.  Since this may make a sinkhole (bathtub?) for water I will build a small mound for each tree.

4) In each hole I will add some agriculture bacteria and each seedling root will get dusted with mushroom Mycorrhizae.  Where to get this?  Fungi Perfecti is not selling the 1 pound bags anymore.

5) I have a tremendous resource for woodchips and will cover each plant hole with a mound of chips to help the soil activity.

6) This orchard is right next to my house so a drip irrigation system will be used when needed.

7) Be ready for retirement in 6 years with something enjoyable to do.