看来没人知道确切的说法。自己在网上搜了一通，
"The short answer to that question is that EAD card holders do not require
employer sponsorship to work, as they are independently eligible for work
authorization."
但是关于Export license 的问题没有答案。但要申请export license 都是在申请H1b
的时候，所以估计不需要。
