
What happens when you brake a paraglider so much that the air speed falls below the minimum speed of about 25km/h?
The photo shows what happens when you pull so much brake that the air speed of the paraglider falls below its minimum speed. The glider stalls. Therefore we sometimes call the minimum speed of a paraglider the stall speed.
Don't do this while flying! Unless you are on an SIV- or acrocourse.
Older gliders can also enter a deep stall when you brake too much - see the chapter on Aerodynamics.

A pre-flight check should be executed...
Before you take off, you should check at least these things: pilot, lines, canopy, wind, airspace.

How tight do you need to pull the leg straps of the harness?
The tightness of the leg straps does not influence the flying properties of the paraglider.
When the leg straps are too loose, after take-off you will find yourself hanging low under the seat and it's more difficult to get in the harness.
Too tight will hinder your movements during take-off, depending on the harness design. In some harnesses it will prevent you from getting into the seat fully.
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.

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

What part is indicated by C (the orange line)?
A diagonal rib connects the upper left corner of a cell with the lower right, or sometimes runs across two or more cells.
This allows the use of fewer lines, reducing the weight and drag of the paraglider.

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.

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 we call the risers that are connected to the lines running to the leading edge of the canopy?
These are the A-risers connected to the A-lines.

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