Some schools ask both recommendation letters and recommendation forms filled by professors. Could I just send them the recommendation letters? It's not very impossible to ask the professors to fill in the English forms for me. Thanks.

it's better that u can send the form, why not fill out the form by yourself but ask for the permission from your professor.

I think it better to do both. Never think an additional recommendation is too much. Recom doesn't have a word limit.

请问一下，recc form上有4个问题，都要简要的写一下吗？还是直接，写上"See seperate letter", 然后让推荐人在推荐的时候把这四个问题头囊括进去，就可以了？

只需要在推荐信里大致包括那些问题就可以了，没必要在推荐表上再填一遍。

那么，全部由自己翻译成E文了？主要是不清楚推荐信到底怎么办，
1、由推荐人自己写好后（当然只有中文的），自己翻译？
2、是和其他申请材料一起寄出，还是单独密封寄出？