Immigration Site

I have 3 questions. Thanks a lot in advance!

1. If I change job (same type) when I am waiting NIW-140 being approved, do I have to let USCIS know if changed my job? (how?) Or, I just need to file AR11 for address change notification?

2. What about if I change job (same type) after NIW-140 approved but waiting for submitting 485?

3. If I go back to my home county (working as the same type) after NIW-140 approved but waiting for submitting 485, can I submit 485 in my homecounty?