How can I maintain valid status if I cancel my EB-5 application?

If you do not maintain an underlying EB-5 investment and fail to file the I-829 to remove conditions on permanent resident status, then you will be out of status in the United States and subject to removal. You may marry a U.S. citizen and obtain conditional green card based on marriage to a U.S. citizen. You should consult an immigration attorney to discuss all issues.

You already have a green card/permanent residency (the "condition" is job creation, but the green card itself is still a green card all the same). If you do not file your I-829 petition when you are required to do so, you will indeed no longer be a permanent resident. Your proposed strategy will require the assistance of an immigration attorney to account for these changes.

You can choose any of the plan(s) you outlined. In reality, you only need one immigrant visa. However, it is highly advisable to consult an attorney to make appropriate choice among these competing plan(s).

If you failed to maintain your investment and remove your conditions, you would typically lose your conditional permanent residency and be ineligible for the removal of the conditions. However, should you marry a U.S. citizen, you would free to abandon your current status and reapply for your lawful permanent residency based upon a bona fide marriage with a U.S. citizen. Once you file your application to adjust status, you would not be deemed to be working illegally in the United States, and you can obtain an independent work authorization and travel document.

Once you renounce your EB-5 conditional residence and remain in the United States, you are out of status. The best bet is to marry so that you are sure you can get a conditional residence reinstated.

If you surrender your conditional green card before acquiring alternate status you will be unlawfully present. Switching from a conditional green card is possible, but generally this has to be done while outside the United States.

You have a lot going on that must be considered. You need to decide if you really want to shut down your EB-5 business or wait until after you have an approved I-829. You may want to keep this business in place and take the new position. I would consult with an investment immigration attorney before taking any action. If you shut down your EB-5 business, you would fall out of status - however that would not prevent you from filing for a marriage adjustment. Generally, you would have your EAD in about six to eight weeks after you file the adjustment.