Answer:
1.) At times, designing a good structure with a specific function may often be difficult. If the structure is not well-designed or strong enough for the function it will not properly work. So in order for the design to be well-built, both the structure and function must cooperate.
2.) Symmetry is a balanced arrangement on the opposite sides of a structure. In order for for a structure to be stable and properly work without complications, it most commonly needs to be symmetrical. This is a very important part of designing a structure.
3.) If the structure cannot withstand the function nor the possible forces that it may encounter. It is likely that it will break or even be completely destroyed.
4.) Shape, line, color, texture, movement, space. The designer may have taken into consideration whom the desk may be used by for the shape and space. Color, texture, and line may have been based on the environment (ex. A carpenter, student, computer desk) it would be in. Although the designer may not have an exact knowledge of where the desk would be, he still could consider what the desk could "possibly" be used for. Once again, the designer could take into consideration the user, for the movement of the desk. If the desk was to be moved around on wheels, or possibly could even fold. The designer must take into consideration EVERY detail.
6.) When people design something, often times you do not know how well that design is going to work without testing it with a prototype. Yes, prototypes are expensive. Yet, if they were to build something without testing their design, something may be wrong with it. So as a result, you will spend more money manufacturing something with a defect than testing it with a prototype.
For question 5, I think it might be best if you answer that one. It is based on YOUR opinion and what YOU use. If you are asked about it, they will know it's from you and your opinion. Lol! But I hope I helped you out with the other questions! ;)