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LDR (light dependent resistor) is a type of input transducer. When light intensity decreases, the resistance of LDR increases and vice versa.
You can redraw the circuit so that it looks like the usual potential divider that you are familiar with. Refer to the video below.
This is a heating curve. So the specific latent heat of fusion here refers to the melting process, which occurs from time 100s to 250s.
The direction of the magnetic field is downwards in the diagram. You can think of a North Pole of a magnet that is at the top and/or a South Pole at the bottom. Since the top is N, and the pole of the bar magnet nearer is also N, as like poles repel, the N of bar magnet will move away and rotate clockwise. The S of pole of the bar magnet will be attracted to the N at the top, hence likewise it will cause the bar magnet to rotate clockwise.
Alternatively you can image the bar magnet to be like a compass needle, and the needle will follow the direction of the magnetic field with N of the needle pointing in the same direction of the magnetic field direction.