F1 OPT to H4 Change of Status - i539 Questions

[WFlcn]

Hello,

I was employed until my F1 OPT until expired on 07/14/2017, and my H1 did not get picked in the lottery. So I'm currently in the process of filing a change of status from F1 to H4, based on the H1b visa of my spouse. I have some doubts in filling out the i539 Form.

1. Part 2 - 2.a., What should the Effective date of change for the new status be?
Should it be 07/15/2017 or any future date before 07/14 + 60 days?

2. Part 4 - 4, Has an immigrant petition EVER been filed for you?
(My PERM was approved while I was working and my employer had filed for my i140 before I quit my job)

3. Part 4 - 19, Have you been employed in the United States since last admitted or granted an extension?
(My OPT got extended last year and I was working till it expired). Please confirm if my response should be Yes.

Any input is greatly appreciated. Thank you.