Am I entitled to recover the amounts I spent to reclaim land usurped from my father's estate, by deducting them from the proceeds of selling this land?

If the land was indeed usurped, the original principle is that the usurper should bear the costs of its recovery. If that is not possible, and the one who recovered it intends to claim reimbursement from the rest of the heirs for what he spent, he is entitled to do so after deducting his share. Selling the land without authorization from the heirs is not permissible, unless the heirs approve the sale, in which case it becomes valid for their shares and the price is divided among them according to their entitlements.