妈妈生病，想让弟弟去办一个来美加急签证，多年没有处理过邀请事宜，有以下问题请教：
1. 加急签证和普通签证办理手续有什么不同？
2. 邀请人除了出具邀请信及个人护照，还需要出具在美工作证明吗？需要给签证官也写一封信吗？
3. 签证人预约签证时除了申请表，还需要同时上交什么文件？
-Check this link for B2 visa application in China:
4. 10年前我给弟弟申请了亲属移民，目前为止还没有来过美国。这个身份签证时有什么注意事项？
-Because it takes a long time for your brother to be qualified for the immigrant visa, it may be fine for him to get the B2 visa, but he needs to report this I-130 on the DS 160 non-immigrant visa (e.g., B2 visa) application form.
There is some information about emergency US B2 visa application in the following links. Although the information is not specifically for the Chinese applicants, I think the principles should be the same. You may follow the information to prepare for the visa appliction and at the same time, contact the US Consulate in China which your brother will apply for the visa from.
Emergency US Visa Appointment | US Visa in Thailand (siam-legal.com)
