I-140 approved!! What next?

Profile: Bioengineer, 1 peer reviews publication with 10 citations, 1 patent, 4 years of work experience on medical devices with impact on millions of patients in the US.

Time-line:

Nebraska Service Center

- September 2025 filed petition
- February 2026 update to Premium Processing
- April 2026 RFE received
- July 2026 RFE response submitted
- September 2026: i140 approved

Questions:
- what is the average time between getting i140 approved ans getting the GC?
- Is the i485 process as challenging as the i140 is?
- can I travel internationally? I am on a valid h1b, with valid stamp for the next couple years.

Thanks!!