I am presently on H1B (first year) and filing a I-140 for an EB2 NIW application shortly. My spouse and I plan to file our I-485 applications soon after that (she is from ROW and hence current in EB2 - we'll use cross-chargeability).

My spouse however is presently on F1 status which will run out on Aug 31, 2011. She is planning to file an I-539 to change status from F1 to H4 starting Aug 31. We want a safety net incase the I-140 NIW is rejected.

1. When should we file the I-539? Is it safer before or after the I-485 filing? (The 539 form does ask about pending 485s)
Does the I-539 need to be processed and completed by Aug 31,2011 (end of F1) or does it just need to be filed by then?

2. Can she complete her PhD studies (by Oct 2011) while on H4?