Wireless and IP Cameras do not mix, a point to point bridge between buildings is nothing like a access point servicing multiple devices.. you always have to have a wire ran between the storage medium (HDD in the NVR) and the camera so nothing external can fuck up recordings.
SmartPSS is free client software that works with Dahua products, allows you to live view and playback recordings over the network and without a browser.. out of the box it's capable of displaying a grid of 36 cameras, you might be able to get more out with a custom designed grid.. ive had no need for that many cameras loaded up in it, im sure it would take alot of load just to display all those feeds.