Q: 是否還有safety check? 一般多長時間
-Very few cases in teh sensitive major are sujected to the background check. So, you may ignore this worry.
去加拿大還是墨西哥, 那個更好?
-Not different. choose the convenient one (travel).
應該帶些什麽文件?
-The H1 approval notice, the copy of the H1 petition materials(i.e. I-129 with LCA document), a employment verificattion letter from your employer (HR) and other required document based on the nonimmigration visa application form (check the US Consulate website.