My responses in order: 1. Green card applications are prospective in nature, meaning they concern what the applicant will do after getting a green card so what an applicant is doing now, before getting a green card, shouldn't matter strictly speaking but switching to H-4 and stopping work could cause USCIS to question whether you intend to work in your EB-1A field after getting your green card. To be clear, however, the risk of this is low and USCIS's concern if raised easily rebutted. 2. Yes but you would need the original receipt or approval notice (combined with your existing visa) to get back in. Make sure to speak with the company's attorney about this/travel. 3. Unlikely, since the EB-1A isn't based on a specific offer of employment but as noted above, a change to a different field could raise questions about whether you will continue to work in your EB-1A field after getting your green card. To be clear, however, the risk is low that a job change in the EB-1A context would trigger an RFE by USCIS.