calculation versus previous week

You need a Calendar table (based on Shipment Date, it should have columns for WeekNo, Year).

Create a relationship to the main table on Shipment Date

For the first table, you should be able to create a matrix with WeekNo, Extraction Date and a measure for SUM( Pallets Number).

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The second table requires a measure using the measure already created so something like:

MeasureX - CALCULATE(MeasureX, PREVIOUSMONTH(ExtractionDate))   

it won't be exactly this, DAX time intelligence features work best with a calendar, so that would involve another calendar table for extraction dates.  OR you could create the previous date by calculating it manually