
When is the best time to put your legs down during the landing approach?
D is the safest option. The others are either uncomfortable and unwanted because you can't use weightshift anymore, or unsafe if you are too late and land on your bum risking a back injury.
Standing on launch you see a rain shower approaching. Do you take off?
D is the only safe answer. You can never be sure that you have landed before the rain arrives, so C is risky. B is only partly true for light rains, but again you're taking a risk. A is not true, although flying in cloud is illegal in many countries.

Which pre-launch check is the most important?
Even though all newer harnesses have a safety feature to prevent you from falling out of the harness if you forget your leg straps, this is very uncomfortable and on an older harness it may be a fatal mistake. Checking lines and canopy is of course very important as well.
See the section on Launching in the Basic techniques chapter.

What do you do when you can't hear the instructor over the radio during a flight?
B is correct, A and C are nonsense of course.
Answer D is the second best choice in case your mind goes blank, you panic and you don't know what to do. It's better to do nothing in that case.

'Big ears' are a descent technique and serve to increase your descent rate. Additionally, in which situation is pulling 'big ears' a good idea?
Pulling big ears reduces the wing area and therefore increases the wing load. This stabilizes the canopy somewhat. It also increases the flying speed but in most cases this is counteracted by the extra drag the ears create.
Which data do you need to calculate the wing load?
The wing load is defined as the weight on the wing per square metre. Therefore you need the total take-off weight and the flat surface of the wing to calculate it. For example, a 25m2 glider flown by a pilot with a TOW of 100kg has a wing load of 4kg/m2.

For a paraglider in the mountains, what wind speeds are considered safe to fly?
Wind results in turbulence in the mountains. While soaring on a ridge or at low dunes or flying in flatlands may be safe up to 4 Bft or a bit higher using a smaller mini-wing, in the mountains a wind speed up to 3 Bft (a maximum of 20 km/h) is the maximum for most pilots to fly safely. Strong winds are considered 25 km/h or over.

What happens when you fly too slowly?
Below the minimum speed or stall speed, the wing stops flying and will descend straight down like a parachute. This is a very unstable situation and often leads to a spin or stall.
See the chapters on Aerodynamics (stalls) and Advanced flying.

A paraglider glides down through the air. But at what speed?
These are all speeds relative to the air!

What is the weight of the fabric used to make paraglider canopies? (g/m2)?
Very light fabric strong enough for paragliders can be as light as 25g/m2. Very strong and heavy fabric weighs 40g/m2 or more.
At around 35g/m2, you can calculate that the weight of the fabric of just the top and bottom sail of a 25m2 canopy is a bit less than two kilos.
Your result is shown above.