Are these sentences and questions correct?

我是一个开心的人，因为我知道我的家庭健康还有开心。这让我一个开心的人。我觉得儿童更快乐。孩子们没有任何忧虑。他们不应该有任何忧虑。

I'm a happy person. I'm happy, because I know that my family is healhty and happy.
That makes me a happy person. I think that children are more happier than adults. Children don't have any worries. They shouldn't have any worries.

Questions:
1. 你的家乡很大吗？
Is your hometown very big?
Ni3 de jia1 xiang1 hen3 da4 ma?

2. 为什么有人喜欢住在大的城市？
Why do some people like to live in big cities?
Wei4 shen2 me xie1 ren2 xi3 huan1 zhu zai4 da4 de cheng2 shi4?

3. 在你的国家最大的城市是什么？
What is the biggest city in your country?
Zai4 ni3 de guo4 jia1 da4 de cheng2 shi4 shi4 shen2 me?

4. 我们怎样让城市变成更好的住处？
How can we make cities better places to live?
Wo3 men ke3 yi3 cheng2 shi4 zen3 me geng4 hao3 de zhu4 chu4?