Hi,
The NIF can be used to connect hosts (example: blade servers) or only can be used to connect to parent switch?
You can connect anything you want to these ports as long as they are 40 or 100Gig compatible.
This switch can be a FEX device of the Nexus 7000/7700 series switches?
The switch can be converted to FEX mode but not sure to what parent switch you can connect it. This may be a question for your Cisco SE.
HTH