(a) Except as provided by Section 310.004(a) and unless the will provides otherwise, all expenses incurred in connection with the settlement of a decedent's estate shall be charged against the principal of the estate, including:
(1) debts;
(2) funeral expenses;
(3) estate taxes and penalties relating to estate taxes; and
(4) family allowances.
(b) Fees and expenses of an attorney, accountant, or other professional advisor, commissions and expenses of a personal representative, court costs, and all other similar fees or expenses relating to the administration of the estate and interest relating to estate taxes shall be allocated between the income and principal of the estate as the executor determines in the executor's discretion to be just and equitable.