Hi,
This is Amitav, Network Consultant @ Bangalore, India.
If the Cisco 3662 router is using optimized IOS software imagesTelco & Telco Plus 12.1, NAT will be possible. Please give the IOS version to be more specific.
NM-16-ESW is L2, it does not have L3. However, routing capabilities will lie in the 3662.
Regards,
Amitav B