As for joining the network virtualized environment to the non-network virtualized environment, Hyper-V Network Virtualization gateways are required to bridge the two environments. See "Hyper-V Network Virtualization Gateway Architectural Guide".
Gateways can come in different form factors. They can be built upon Windows Server 2012, incorporated into a Top of Rack (TOR) switch, put into an existing network appliance, or can be a stand-alone network appliance. F5 has announced one such network appliance (F5 To Deliver Microsoft Network Virtualization Gateway).
If you are looking for Technet reference, click on "Network Virtualization technical details".