They call them 66/80 because they are really 66cc (some are 68). The Chinese call them 80cc because they measure the combustion chamber, but that is not the correct way to measure displacement. Displacement is what you call the size of the cylinder, normally measured in cubic centimeters for small engines and liters for bigger engines like cars and trucks. So the actual displacement of your engine is 66cc, or cubic centimeters. Now as far as starting with the push of a button, that would be what's known as electric start. At least one person claims to have built an electric start for the Chinese two strokes, but he never shared how he did it and he hasn't been around the forums for a long time. Honestly though, if you're 15 and already too lazy to pedal a bike to start the engine, you're going to have problems in life. The pull starts they sell for these engines are junk and break very easily. If you really want to install one, you will need a wider pedal crank. A lot of vendors sell them and they're not hard to find. But the 4 stroke kits come with a pullstart that isn't junk like the 2 stroke ones are. You will still need a wider pedal crank to use a 4 stroke. Now as far as the bikes with the chain going to the pedals, they have something called a shift kit installed. The shift kit adds a jackshaft to the bike, which allows the engine to use the bikes gears as a transmission, thus giving the rider more than one speed for motoring. As far as which is better, everyone has their own opinions. Some love the shift kits, others feel they require too much maintenance.