Can a DACA beneficiary apply for EB-5?

You need to show that you are eligible to adjust status in the U.S., or that you can leave to consular process for your final interview, without triggering an unlawful presence bar. If you can get advance parole that may help with the adjustment option.

Yes, you can apply.

You may be eligible to file your i-526 petition, but unless you have valid nonimmigrant status (DACA does not count), you are not eligible for adjustment of status. Once your I-526 petition is approved, your case will be sent to the appropriate U.S. embassy or consulate in your home country. As long as you have not accrued 180 days or one year of unlawful presence in the United States and are otherwise admissible to the United States, you should receive your immigrant visa and be able to enter the United States as an immigrant/permanent resident.

You can file the I-526 in the U.S. but you will need to consular process for the immigrant visa.

Generally, DACA beneficiaries would not be eligible to adjust staus to EB-5 because they lacked lawful status. Other visa categories may offer an exception to this. The inability to adjust status may not affect eligibility to consular process. I hope this helps.

Yes, but you would still accrue unauthorized status upon turning 18 and would have to apply for an immigrant visa abroad and best to depart the U.S. within six months of turning 18.

In theory, yes, but unlawful presence issues may preclude a successful result.