Yes
如果是J1,在簽的時候就要確定有效期是多長時間嗎?還是有固定的期限?
Usually it is three years
是不是過了有效期就要回國?
Yes unless you 延長或轉成別的簽證.
需要回國簽嗎?
Not really.
聽說J1結束後要等2年才能再簽美國。是這樣嗎?有什麽限製?
Yes unless you get waiver
J2簽證需要什麽材料?可以本人先申請了J1再給家人申請J2嗎?還是最好一起前?
It is up to you
如果是H1,短期三個月。是在H1的簽證有效期結束後就要離開美國嗎?
Yes.
還是可以待多長時間?
10 days no gap.
工作合同有多長就待多長,是嗎?
No. One period is three years.
回國就要再辦簽證?
It is up to different situation.
H4簽證的準備和J2有什麽區別?那個更好辦?
I think it is almost same thing. J is a little faster.
公司打算讓我幹幾年,J1和H1哪個對我和家人更好些?
J does not need to pay tax. For GC, H is better.