Can a 14 year old boy who has not been vaccinated enter to the Memorial with the Excelsior PCR Pass?

Yes, He would. But everyone over the age of 18 has to provide proof of vaccination.

I wouldn't know. I do know they ask for proof of vaccinations everywhere in New York

When I was there on Friday, there were many young children inside the museum, who as of now are not vaccinated due to age. All the kids were required to wear masks. So I think it depends on those who are eligible for the vaccine, must show proof of it. If your son is eligible for the vaccine at his age, he must show proof, like all the adults. Otherwise, I think he just needs to wear a mask.

Yes, the memorial is outside and open to anyone. My wife and I was there last weekend and no asked us . We didn't go in the museum though.

I don't think so. They are checking vaccination certificates