Yes. A hard clutch is an indication of a worn out one. Time to replace. You will have to replace the clutch plate and the pressure plate. While changing, have the workshop look at the release bearing and the condition of the flywheel.
Costs are expected to be somewhere around 12 K.
Maruti Alto 800 has a tank capacity of 35 litre, to know that how much petrol is left in the tank, divide 35 with the total no. of bars say 10, then if the fuel gauge indicates 2 bars it means there is 7 litres fuel left in your tank.
it is the pulling power of an engine, the difference will ideally be known when one closely observe the difference in initial pickup. final pick up may be the same for both engines as the difference will not widely be known. Normally firing of the diesel will be slow when compared to petrol. therefore higher horse power engine gives you more power when initial pickup is demanded which suits city driving , where frequent breaking, start and stop is more. an engine with 110 ps with AMT is a good bet for city driving.