No problem. They work 24 hours a day 7 days a week.
2.如果想尽快返回美国, 需要带些什么文件呢?
I assume that you are holding H visa. If so, you'd better bring your valid I-94 plus H approval notice.
Picky officer may also ask for current paystubs. No harm to bring a letter from your employer stating your are currently employed.
When returning four months ago from Montreal to NY, I was only asked for I-94, which was replaced with new one at the port.
Good luck!