关于课余活动什么内容

回答你第二个问题，

如果你选择waive your right to examine the letter，那就是说你的推荐人直接把推荐信发到学校，你不会有机会看到信的内容了。

我觉得差别不是很大，毕竟recommendation letter的weight不是特别大。

The more, the better.

Not only you have to show that you are involved in community (while busy at school and work), but also you have to show that you have a goal and you are persistent with your goal (whether it's social or community). Demonstrate you are a leader throughout community, and you have made a impact whatever you are involved with.