I`ll answer the second one first....about £40
As for your first question, there are several reasons why an engine will smoke.
The first thing we need to do is identify the colour of the smoke, Blue, Black or white.
If the smoke is blue, it means it's burning oil. This could be caused by valve stem seals, worn rings, a plugged PCV valve, not changing the oil for extended periods, too high of an oil level.
If the smoke is black and there is a smell of petrol, it could be the spark plugs, the ignition or the wrong mixture in the carburetor.
If the smoke is white and has no real smell, it's likely that the head gasket is blown, and your burning water. This is usually caused by overheating the engine and usually causes the oil to be saturated with water. White smoke can also come from a leak in the intake manifold , allowing water to be mixed with the incoming air.
Assuming thats its oil thats burning, cos thats most common, then yes it could be rings but its more likely to be the valve stem oil seals.
Whip the rocker cover off and do a visual check, are all the seals seated properly or is one or more sliding up and down the valve stem? Give them a prod, are they flexable or rock hard?
