So let me make a few suggestions to help give you ideas for responding to these questions. With the first question be sure to describe what you see younger people such as yourself wearing and compare that to what your grandma or a friend's grandmother wears. Remember you want to describe common clothing for both groups, young and old.
For the second question, if you cannot go very in-depth on your opinion of whether students like uniforms as a whole, consider saying that some do like uniforms because......fill-in the blank.... but most students don't like wearing uniforms because ....fill-in the blank. And remember, even if you don't have strong feelings about the question you must express an opinion and support it to satisfy the evaluator.
For the final question, I recommend you think of 3 events that people would dress up for and explain why people want to look their best for these event or if you can only think of two then go into a little more detail on the importance of looking your best on those occasions.
Good luck with your preparations. :) e.