Engine Cooling problem
2000 Other Fiat Models 6 cyl Two Wheel Drive Manual 73000 miles

My vehicle is Fiat siena Weekender(almost Fiat Adventure model, india),

1 the cooling fan runs at the maximum temperature only(needle in the last), its not running in half mark?
and slight coolant leaks occur from the tube joints on high pressure, can i run the vehicle in the same condition ?

2 What are the ways to get good milleage, the car is 16 V Engine, almost 1600 cc, petrol version.
it gives 9kms per litre only.

3 Iam planning to connect the auto gas kit, will it run without problem ?

Advance thanks pls suggest me sir.

regards,
shankar