Answer 1

不难
英文或者中文都可以
因公的话基本上没什么问题
只要你说出去的地点时间以及回来的时间地点就可以
因私可能稍微麻烦点

Answer 2

not very easy.
they will ask you why you go to USA.
and what you do there and whether
you come back or stay in USA for
good and so on...