Upvote:1
While each of you would apply for your own independent ESTA, you are able to group the applications and make one payment.
It may take only moments to be notified that the applications have been accepted, although it can take longer, up to 72 hours. Your ESTA validity starts on the date you are approved, and is generally valid for two years (multiple entry) or until your passport expires, whichever comes first.
As you are in the country (and USCIS is aware of that), it makes sense to put your US contact information.