Please show a photograph of the actual site where the pavers are going. Show some surrounding area in the photo so we can gauge where the water might be flowing for drainage. Before talking about HOW you're going to install them, let's find out WHAT you are trying to accomplish. What is the purpose of this paved area? Based on the plan you've submitted, it doesn't look like parking.

This area was previously landscaped with rocks and shrubs. I've since removed the shrubs so I could get my skidsteer to the backyard.
As mentioned in the topic title, it'll be used as a sidewalk towards the back, a place for trash/recycle carts, and firewood.
Drainage should not be an issue. Looking at the drawing in a N/S/E/W compass manner, the north side slopes fairly steeply towards the backyard and gradually decreases in slope as it gets out to the field. The east side currently slopes towards a neighbor's house but the area between our houses is a drainage channel that goes to the backyard.
Does this address your concerns enough? or did I miss something?
Thanks

"Does this address your concerns enough?" Not really, because you are not adequately describing degree of severity. A picture would give an idea of HOW MUCH slope and what things and how much space are in the area. It would be a better way for me to predict complications, or to determine if there is an easier way than what you are proposing. I want to see how much slope and what other things there are in the work vicinity. Is there a fence between the properties? How far to the next property? A simple picture would probably show all these things without me needing to think and ask about each thing. There are aspects to your drawing that I don't understand. A picture of the site would likely make it easier to speculate what you are proposing.

It sounds like you're building a retaining wall. Is this really necessary? (A picture would probably tell!) I'm going to speculate that it isn't unless the grade change is severe. In that case it would be preferable to have the wall outside of the paved area ... not underneath the edge soldier course. Placing it under adds complication to the compaction process. What is the paver pattern? If minimal cutting is a goal, the retaining wall will create another complication.

For pedestrian and light duty vehicular use, 6" base is overkill. 4" is sufficient. If you're going to be driving a skid-steer across on a routine basis, then 6" well compacted base might make sense. Where are you located?