In addition to the powers listed elsewhere in this Division II and any powers given by local law, the Baltimore Authority within its area of operation may: make mortgage loans; make rent subsidy payments to or for persons of eligible income; make construction loans and long-term mortgage loans to any person to produce housing for persons of eligible income; and purchase and insure mortgages secured by housing for persons of eligible income. Not more than 80% of the residents of a housing project may have incomes above the levels for persons of eligible income. The listing of powers in this section does not imply that the exercise of those powers by the Baltimore Authority before July 1, 1990, was unauthorized. The power of the Baltimore Authority to rent housing to persons of eligible income is not limited by § 12-402 of this article.