Yes, the wooden bridge [
binged.it] was built to get SP electric trains from Berkeley onto the Bay Bridge, and they started using it in 1939.
Bay was filled west of the SP main in... the 1930s? 1931 aerial pics are online and would help answer that.
All? passenger trains out of Oakland Pier that headed toward Sacramento stopped at 16th St.
WP 3rd St was a WP stop as long as WP had passenger trains.