Are these sentences correct?

I am clear that you cannot type the tone mark by the keyboard, there is a way to solve it.

You can write like this: Wo1 zui4 da4. Tone mark is very important for Chinese.

1. Wo3 zui4 da4 de yuan4 wang4 shi4 wo3 de jia1 ren2 bao3 chi2  jian4 kang1. (My biggest wish is that everyone in my family stays healthy)

Family in Chinese means 家， however, it also means family members=家庭成员/家人。

2. Wo3 bu4 chang2 chang2 chi1 kuai4  can1. Yin1 wei2 wo3 bu4 chi1 rou4 le. Suo3 yi3 wo3 jue2 de kuai4 can1 guan3 (fastfood restaurant) mei2  you3  hen3 duo1 hao3 chi1 de fan4 cai4.
3. Wo3 xi3 huan1 jian3 dan1  de shi1 wu4 . (easy food), easy mean 容易, 容易 means not difficult. easy also means 简单，which means not complex, Here 简单 is better.
4. Wo3 shang4 wang3 mai3  yi1 fu.  (I buy clothes on the internet)

5. Wo3  xi3 huan1 xue2 bie2 de ren2 wen2 hua4.=人文化？

Xiexie! Thank you.

1. Wo zui da de yuanwang shi wode jia ren neng baochi jiankang (My biggest wish is that everyone in my family stays healthy)

  我最大的愿望是我的家人能保持健康。 (家 = home; 家人=family members)

2. Wo bu chang chi kuai can. Yinwei wo bu chi rou le. Suoyi wo juéde kuai can guan (fastfood restaurant) meiyou henduo haochi de fan cai.

  我不常吃快餐。因为我不吃肉类，所以我觉得快餐馆没有很多好吃的饭菜。(尝=taste, try)

3. Wo xihuan jian dan de shi wu. (easy food)

  我喜欢简单的食物。(容易 means something is easy to do, you can only say the food is 容易做的)

4. Wo zai wang shang mai yifu shangwang (I buy clothes on the internet)

  我在网上买衣服。

5. Wo xihuan xue bie de ren wenhua.
  我喜欢学别的文化。