1.yes
2.no，结束时间不变，换言之，如果EAD批准时间晚于你申请的开始时间，你能使用的
OPT就不到12个月了。
3.The application for the 17-month OPT extension must be received by USCIS
prior to the expiration date of the student's current OPT Employment
Authorization Document (EAD), and no later than 30 days after the student's
ISSO advisor signs the OPT extension recommendation on Form I-20.
