How can I apply for EB-2 and EB-5 concurrently?

You will become a permanent resident on whichever application is first approved. You can then inform the other that you are a permanent resident and that you will not be pursuing the second application.

You can absolutely apply for both if you disclose this. If your EB-5 is approved first you get a conditional green card and if your I-829 is denied, you may be able to re-immigrate via the EB-2.

You can certainly have both applications be filed simultaneously. They are both immigrant intent visas so there is no issue there. However, when you are ready to adjust status you will need to decide which one to go with. Due to severe retrogression for Indian citizens with EB-2, most likely your procedure will be finished through the EB-5 process. If there is a problem with your EB-5 at the I-485 approval or I-829 approval stage you can always fall back to the EB-2 application and adjust status when your filing date becomes current.

You can have multiple EB cases going, but only one adjustment of status application at a time. You can transfer an I-485 from one EB case to another, provide both have a green card available. This will require some careful planning so please consult with an immigration attorney.

There is nothing to prevent your employer from commencing a case to qualify you for lawful permanent residency under the EB-2 preference at any time. It will in no way impact your eligibility to adjust status, based upon the approval of your EB-5 Investor Petition on Form I-526, by filing your application for Adjustment of Status on Form I-485. If and when your application for Adjustment of Status is approved and you become a permanent resident, as a practical matter, your EB-2 application would be moot and irrelevant, and there would be no reason why your employer would want to continue. However, as you indicated, out of an abundance of caution, your employer could continue, just in case your application to remove conditions on Form I-526 is denied. Also note that even when your EB-2 Preference Petition is approved on Form I-140, you would be subject as an Indian-born national to a backlog under the quota of 10 to 15 years, before a visa number would be available to qualify you for lawful permanent residency on that basis.

You can have both immigrant petitions based on EB-2 and EB-5 filed, but you can only choose one or the other as the basis for proceeding with the I-485. The EB-2 based immigrant petition is granted to the employer, so unless the employer wishes to cancel it, it will not be voided by you opting to proceed with the EB-5 for your adjustment of status.

Yes, you may file concurrently, but will have to choose either EB-2 or EB-5 basis to adjust status (or consular process). As you know, EB-5 gives you a 2-year conditional green card and you have to remove the condition in the future by filing I-829 and proving requisite job creation to become a permanent resident, whereas EB-2 gives you a permanent green card. EB-2 is significantly backlogged for India though.

You may only have one green card but both cases can be filed at the same time. Once the EB-2 I-140 is approved that is yours to use later if I-829 is approved.