Depending on one's build, it's probably not possible to get one's hands really light on the bars. For the quad thing, try pulling back more at the bottom and mostly unweight the backstroke pedal so the downstroke leg doesn't have to lift it. A good way to get the hang of that is to pedal very fast in a very low gear. One should be able to pedal at least 120 rpm without bouncing in the saddle. Back when I was really training, I used to try to do that for up to 45', once a week. The idea is to correct one's pedal stroke so that one is only applying force tangent to the pedaling circle, i.e. normal to the cranks. Using more of one's leg muscles increases endurance.