Since this diagram doesn’t specifically label L1 and N, you have to assume that they are following the normal wire color convention. You’ll notice that the wire colors are noted at the power supply (BK and W). Which color is normally used for Neutral?
Once you know that, you should be able to figure out Q. 4.
For Question 10, you can figure it out using a simple Ohm’s Law calculation. There is a spec on the heating element in the written information – do you see what it is?