Wife's h1b status Vs H4

Question

Having applied for h1b in March, my wife had to travel to India due to an emergency on 30th april. Her h1b status was pending then.
She went for H4 stamping on 18th jun 2013. After a week she got her h1b visa approval in USA.

She came back to USA on H4.

1. Can my wife work on h1b from 1st Oct?
2. I would like to know how I-94 works and what is the cost?
3. What would be the next process to get her status back to h1b?

Answer 1

1. No
2. It cant be ammended, employer should file the status change, she can't do herself
3. I suggest her to back to India and apply for H1b