H1 to H4 COS: Urgent help needed

[gspradeep]

Hi,

I need urgent help regarding COS from H1 to H4.

I currently working on H1B and my daughter is a dependent H4 under my H1B.

I am planning to quit my job and do a COS to H4 (My spouse is also on H1B).

Question:

1) I researched and found that I should be filing I-539 to do a COS. Please confirm/correct.

2) In my case, should it be 2 separate I-539 forms for myself and my daughter?

or

Could we do the same form for both of us?

Would the filing fees $290 be for each applicant or together?

3) After filing H4 with USCIS, When can I quit/stop working?

Thanks.