How old is the car?

Full comprehensive insurance I think is only given in the first year - or maybe its up to 3 years old. Can't quite remember - maybe someone else can help there.

Third Party here can mean a variety of things.

You can take out additional passenger and driver cover, liquor cover, off road cover etc etc

Depending on the make of car the insurance company put on excesses too.

Insurance is generally regulated by the Govt so insurance companies can only offer what they are allowed to - hence offering the same.