1. You are expected to be in a valid status in order to be AOS eligible - how you remain in a valid status is something you will have to figure out on your own - I don't provide guidance on that.
2. See response 1 above.
3. No, you can't do that. Entering the US on a NIV with a preconceived intent of filing AOS is frowned upon - it is considered a fraudulent use of the NIV.
4. Depending on your CN and when it becomes current, you may be able to file AOS, while your spouse processes FTJ (follow to join). Alternatively, you all file CP.
5. You need to go through the AOS Process Spreadsheet first. Get a better understanding of a DV based AOS process before trying to figure out when to make the DV payment, especially in view of the potential complications you have.
6. It is recommended.
7. He may. Admission or re-admission to the US is never guaranteed to a non USC, it is always at the discretion of CBP.