Interview H4 holder

I am a Spanish Psychologist and I want to work in the US. I want to ask for advice about when should I say that I’m a H4 visa holder in a interview: Should I tell it after the interview or at the beginning? Should it appear in the resume? How to tell them that I could afford the cost of the process?

Another question is about the process: How much time must pass after they agree until I can work for them with the H1B visa? Could I work during the process or I have to wait until it is finished?

I am living in Nashville so I would appreciate any kind of advice about my situation.

Thank you very much.