It's sunny on launch and you're ready to take off, but the wind has been from the back for quite a while. What do you do?
Gliders suffer the most from direct sunlight. The airtight coating is damaged by the UV-radiation. Don't leave your glider out in the sun unnecessarily.
Additionally, sitting on the reserve parachute may damage it without you noticing, so it might fail if you ever need it. Never sit on your harness.

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.

Why are the cell openings slightly pointed down?
The cell openings are positioned where the air flow hits the profile of the airfoil.

You're on a straight course and you don't need to change direction any time soon. What do you do with the brake handles?
Modern paragliders fly best without any brake applied - at the so-called trim speed.
But by applying a little bit of pressure, you take out the slack in the brake lines. You feel better what the wing is doing and you can react quickly and subtly to keep the wing straight overhead. This is called active flying.
If you have some more experience it doesn't hurt to let go of the brake handles and relax, but only if it's safe to do so.

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.

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.

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.

'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.

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

We lay out the canopy in a semi-circle before take-off. Why?
When the center cells fill first, the canopy will rise steadily and straight.
Your result is shown above.