The main function served by Cisco WCS or Cisco Wireless Control System is serving as a comprehensive platform to meet the needs of small, medium and large-scale wireless LANS in local, remote, national and international locations.
Providing PoE
The Cisco Power over Ethernet (PoE) switch allows connectivity to ethernet-powered devices including wireless access points, video cameras, and Cisco IP phones.
No it does not.
Data, Voice, or Video -courtesy of Cisco Net Academy
The Cisco Aironet wireless adapter is used for data communication between fixed, portable and mobile devices using both wired and wireless infrastructure.
loading Cisco IOS software
A small office PBX is a telephone system that has a variety of benefits and functions. They increase productivity with applications such as Cisco Unified CallConnector which is used for Microsoft Office.
The Cisco 7206vxr is a router switch so its purpose is to perform that function on a network. This device is available for purchase at the website World Wide Supply as well as Pinnacle Micro and Infinity Micro.
Cisco Technical Documentation
DHCP Relay, called a helper-address in Cisco systems.
Some recommended books about Cisco routers are: Cisco Router Configuration, Cisco Routers For The Desperate, Cisco Routers for IP Router, Cisco CCNA Routing and Switching.