Consindering Buying a Golf !!

Hi all

I am in the market for a new car and thought most of you people would be pretty up to date with your facts.

Any way the car i am looking at is a 1999 VOLKSWAGEN GOLF 4th Gen Rally

Here is a link to the exact car : http://www.carsales.com.au/pls/carsales/!cs_content.dealer_vehicle?vehicle_id=1765662&current_rec=1&total_rec=1&sort_type=1&make_id=15&model_id=147&state_id=4&region_id=171&search_distance=25

What I would like to know is there any thing in particular (any faults) I should keep an eye out for when buying a Golf ?

Also which is the better engine the 1.8L or 2.0L ?

Do Golfs respond well to mods if so what is the best mod to give a performance boost.

Thanks

Any other input or anything that you can add will be appreciated.