Relevant Calculations

I have identified these kpi's:

Age of inovices unpaid, because unpaid invoices may attract any penalty ( few vendors may do so)

Number of invoices by BU / By Age (Paid and Unpaid)

Paid invoices Age when the get paid

for this data see: https://drive.google.com/file/d/1aHULztI9Q0Ho7ffoRcBceAiElOTIZVji/view?usp=sharing

Please adise what calculations/dax would be relevant?