Two general questions,
1. What are the benefits of filing an EB2 NIW for a person whose I-140 has already been approved by an employer in the same category apart from NIW, not depending on your employer? Also, can you get your I140 approved priority date to your NIW?
2. Is it possible to renew the H-1B visa stamp before expiration? For example, if my H1B expires on November 1st and I apply for a visa stamp in October with approved extension I797, Would I be able to renew it?
While an approved I-140 with an employer offers some benefits, an EB-2 NIW grants portability - you can keep your green card across job changes in your field. It also allows extending your H-1B past the 6-year limit and enables your spouse to work and travel with you. For those with backlogged priority dates (e.g., India), NIW can help with I-130 petitions in specific situations. If your I-140 is approved already, the main advantage of NIW becomes self-sponsorship. Finally, you can renew your H-1B visa stamp before expiry, though consulate lead times (like four months) might apply.