The lip tucks around that piece, so it sits behind the physical lip (whether that's the stock trim or the dynamic trim). It connects to the inside of the bumper cover and something else towards the engine (I can't remember off the top of my head). If I remember, I'll try to get a picture of it in the next few days.
Yes, #8 is the plastic piece in front of the metal cross member. I just had mine all apart trying to get the lip (#5) re-attached, it is like a big jig saw puzzle trying to get everything snapped back together and a few screws in the corners. I also replaced the cheesy splash guard for the second time.