Just quickly... I2C needs pullups not pulldowns
Also i'm looking at the TI datasheet for the PCF8574 and it suggests that the full address is not 0x32 (32 is actually the decimal value from the table)
According to page 4 it should be combined with the read write.
If I was you I'd forget the LCD for the moment and just connect the PCF8574 to some LED's. Once you get the address and the communication worked out connect it to the LCD.