Errors occurring during pipetting?

Ah - the often-overlooked problem source. Well, pipettors use a disposable plastic tip. Here's a simple test that can put you on the track. Take a straw and pull up some water into it, mark how high it got, then blow it back out. Now pull up the same amount of cooked oatmeal (more dense) and blow it out. Now pull up the same amount of honey (more viscous) and blow it out. What happened with the oatmeal and honey? Did they behave the same as the water? The other two parts are more logic problems: , but you can try using the straw to deliver water held vertically and tilted and see if that gives you an idea for c and for d, I think what they're looking for is the difference between 10 measurements of 0.1 mL and 1 measurement of 1 mL (hint - it's all about errors, right?).
As for over- and under-winding, there are a couple possibilities here - but I suspect they're looking for something related to calibration range. As for checking the calibration, one way depends on the fact that 1 mL of water weighs 1 g.