yes 4 grey ones are injectors,

regards the white plugs, one will be idle speed control valve the other will be crank sensor. is more than likely that the plug with the longer lead is the ISCV one, you could pull back the boot on the plug to see the wiring, on the ISCV it should be black/red and brown/yellow.

the car connection is normally near where the relays are (relays control the power to the ECU and also power to the fuel pump) as these are control via the ECU.

The main car connectio usually has 4-5 wires on it. (black, black/red, green, brown/white and possibly brown/green