1) What are the short trailing lines at the end of the wings for?
Discharging the static electricity that builds up on the aircraft in flight.
2) What is the short cable between the wing and the aileron?
Static electricity bonding.
3) Where are the pitot and static drains? (are they on the 152?)
No, they aren't.
4) What does LL mean in 100LL? I can't find it anywhere!
Low Lead (but not unleaded!)
5) What are the different aerials on the fuselage? I assume it's the VOR, radio and transponder. Are there any more on the 152 and in what order do they come?
In a normal C152 layout :
The two on the top of the tail that point backwards in a 'V' shape are the VOR aerials.
The little shark fin one underneath the aircraft is the transponder. The one on the roof of the cockpit that slopes backwards, is the VHF communication radio.
Others you might notice on individual aircraft although they're not standard fit on all aircraft : a wire stretching from the cockpit to the front of the vertical fin is an ADF aerial. A rectangular/square boxy shaped one beneath the aircraft is a DME, and a similar shaped but slightly smaller one on the roof of the aircraft would be a GPS.
6) Are any of you going to the International Careers in Aviation Exhibition a week Sat (the 10th)?!
Not me I'm afraid.
One final important thing I would like answered - what would you guys say is the standard safety briefing for passengers on the 152? As you have told me, it needs to be said to the examiner when he gets in....
"Welcome aboard sir, before we get under way today there's a few safety aspects I'd like to go over with you. The doors are located on each side, they're operated very simply by pulling this handle here, please remember if you're exiting the aircraft not to walk forward of the wing. The seatbelt comes in two pieces, a lap belt which is done up like so, and the shoulder harness which clips onto this little buckle like this. Please keep your seatbelt on and secure throughout the flight. I'd like you to note at this time, the location of the first aid kit *
here* and the fire extinguisher *
here* If you have a mobile phone on you, I'd like you to please switch it off now. Finally, please let me know if you're feeling ill or uncomfortable at any stage in the flight and I'll do my best to help you'
don't use the word 'sick', it doesn't sound cool and professional 
The only things you're legally required to cover are the position and operation of doors and the seatbelts (unless you're flying over water, in which case you will of course be carrying lifejackets, and you will brief your examiner on how to put them on and use them). It's also OK if your examiner has already got in and buckled up, to say 'I see you're already familiar with the operation of the doors and seatbelts' and carry on from there. The rest is just point scoring and they can't fail you for not covering it, but if you can reel it off and sound like you know what you're talking about then you've just made a favourable start to the flight. I'd rather have my students give a bare-minimum passenger brief that sounds competent and knowledgable, than a big elaborate one that is obviously being done parrot fashion.