Ahleong, nice attempts to shoot there. Got some comments for you here...

The RQ with umbrella is hard to get the good exposure on her face, so if you manage to find someone to hold an reflector there, that would be great.

Then the panning shots (don't think you pan too much, eh) not look panning at all. The shutter speed too fast to freeze the cars in action. They are like parking at the tracks.

Just my 2cents here, mate. Nice attempts! Some shots are great! Particular like that shot from the crowd!

I think Vyruz gave the brief info on panning shot. Just try to shoot more. You are not limited to shoot those cars in the circuit. The cars on highway also can get panning shot well.

Abit of advice is, try different shutter speeds on panning shot. Then you can check the RIMs and background for the panning effect.