My thought would be yes.
I will add that my experience in Ski Areas is if woodburning fireplaces are allowed. Allow for a pile of firewood, even with the snow load.
To answer the questions requires detailed information on the subgrade soil profile to a depth of at least 4 feet, and then the answer will only give direction for you to pursue.
-- Such information would include: water table, with seasonal variations.
-- Soil classifications (sieve, possible...
1/2 inch movement in an 8 to 10 ft high wall is not out of the normal. The idea there will not be movement during and after backfill compaction behind this type of wall is not reasonable.
As one who deals with frost heave, as well as insulation issues, I ask:
What are the shallow ground water issues?
What are the site drainage conditions?
Can shallow or deeper soil moisture continually migrate beneath the slabs or foundation elements and freeze?
Will the "ledge below the soil"...
Yes, if excessive quantities are present, it could be a detriment.
My father, back in the 1960's, considered a wall base keyway to be an excellent collector of construction debris and such.
He taught me to avoid them.
Driven Piling overcome both skin-friction and end bearing during the driving process.
The driving process ends when the element has encountered sufficient bearing, side & end OR the depths are beyond the project budget.
A drilled pier can be placed under a number of criteria for length but...
A section showing the original ground surface would be nice.
Also, any drill hole data and info on the site geology
Surely, something this size has a decent study behind it.
Removal of the clay backfill area and replacement with a free-draining material (A57 stone is one such) would be my recommendation. After the wall has dried, the staining on the CMU can be 'washed' off, over a period of time.
Assuming the staining in the basement corner is adjacent to an...
Unless specific sizes are required, such as water movement, soil to or from sand/gravel filter
I have used 3",2",1.5",1",3/4",1/2",3/8",#4,#10,#20,#40,#100,#200 and hydrometer for .02 & .005 mm
This has worked for me in Western Colorado, USofA