1) we don't tell a customer how to run his vac pressure

2) By target down force I assume you mean the margin on the JD monitor? Again, I just hopped in the cab with the customer I don't know why he chose the settings he was running but they appear to be doing the job. 

As shown on his JD monitor, the minimum margin (net force on the gage wheels) was 54 lb on row 9, max was 88 on row 3, avg was 77 lb across the planter.  Traveling as slow as he was (4.5 mph) and in a field with areas of blow sand that had been Turbotilled, he likely did not want much more to avoid gage wheels leaving a depression in the sand. 

As long as the margin never went below 50 lb I'd say he was doing a very good job and maintaining consistent seed depth in these widely varying conditions. Maintaining a min of 50 lb in the hard clay no till portion of the field required a lot of hydraulic pressure and weight on the planter wings. Why use more than you need? There are rocks in this field.

3) I don't know.

I was hoping you would ask about the why cast iron gage wheels.... ;-)

Jim at Dawn