Could a memorial to the victims of the attack be incorporated into the mosque building?
a) Why would it?
To honor the victims and recognize that Islam did not attack the WTC. Why would they need to recognize that Islam didn't do the WTC attacks? Every level headed person knows this, particularly, American Muslims.
Why would the victims need to be honored at this community center? Were the victims honored, or a memorial build at other religious centers, or churches?
b) What other businesses in the area have a memorial?
This is not a business.
It's a nonprofit, but it would still rake in money to pay staff, and afford upkeep.