ACI brings many of the benefits of cloud automation tools and Software Defined Networking to Cisco data centre switching.
See these excellent range of videos on the technology from Netpro's sibling web site Cisco Learning Network for details.
https://learningnetwork.cisco.com/community/learning_center/aci-training-videos
Yes the N7K has L3 capability assuming that you purchase the appropriate software licenses and line cards.
It can be used for a number of different purposes including access tier, distribution tier and core tier functionality.
