Yes there are 2 connections, wired & wireless. Whichever you decide to use for your application is the one that needs to be set as "default". I do believe they can be used at the same time, however not reliably.
If you leave wired for the default, and connect with the wireless connection. If the camera ever reboots, or anything like that it may not connect back to the wireless. That why only one can be the "default".
Connecting your NVR here will be the same as any other location, simply minus the Internet. Run a wire between the NVR's LAN port to one of the LAN ports on the router. The NVR MUST be on the same network as the cameras in order for them to connect.
You should have no issues connecting to the web UI of the NVR as long as your PC is within the same network as the NVR & cameras.