Marbon

1- Select no. They will understand what it entails
2- You need to fill in your ex spouse personal information and last known address - It is basic name address bla bla
3- It doesn't matter. Blank or N/A, again they will understand
4- No, your ex spouse doesn't have to fill part 8, leave it blank. This is a single petition.
 

You will never know for sure if you were approved at the interview, even if they say it straight out, you can't know for sure. You will only know once your status changes to issued. You just have to wait for that to happen.

Your status will not change to "Issued" until the medical exam has been received, all documents from the interview are reviewed, and all administrative processing is complete.  At that time, your status should change to "issued". At that time, you can consider it "approved".  Good Luck.

Confirm with the clinic when your medical was sent over. Make sure it wasn't held up. Don't expect London to go back to your case the dayit was sent over. It has to get sorted and to the right place and the officer has to get back to it. He could take a week or maybe only a few days.  Takes longer because you kinda got out of the flow so to speak. When your status changes to issued, you are approved. They still have to pack up your white envelope to be turned over to the courier, along with your passport. The courier has to pack them both in a delivery envelope according to the delivery address you chose, then email you. Expect 3-4 days after "issued" before you receive it. 

Yes usually you should fill in the ds-160 after the embassy has received your case that's why it's says not ready. After they've received it you'll get sent packet 3 (i got mine the day later). you can track you're case on ceac on the immigrant section and you'll see when it arrives. You can book your medical as soon as you have your case number 😊