Altering the date of the statewide primary election in the year in which the President of the United States is elected; altering the date of the primary election for municipal offices in Baltimore City in the year in which the President of the United States is elected; altering the deadline from 6 to 9 days after the filing dates for filing a petition to challenge a candidate's residency; clarifying specified provisions of law concerning the filling of specified vacancies in nomination; etc.