1) nafaqa "to sell well; find a brisk market; to use up, to exhaust one's stores," and in Form IV, the form used here, means "to spend, expend, disburse; consume, use up, exhaust, dissipate." It refers to the total dissipation of the khazA'in (plural of khizAnah) the "treasure houses; vaults, coffers, safeboxes; treasuries."2) "yakUnu khazA'ina al-arDi kull*hA" can probably be read in two ways: either accusative (kullahA) or genitive (kullihA). The former would modify khazA'in, and would be translated "all the treasures of the earth." The latter would modify arD, and would be translated "the treasures of the whole earth."
3) The verb thabata as used here (form IV) has the primary meaning of "establish," but with the connotations of proving a truth, as in "to corroborate, confirm, substantiate; to bear witness."