such an interesting task, I'd like to have a project like that. And it's not only about money :)
So, the big difference between security and network guys you can see in the comments here. Nobody cares about scalability, reliability and future upgrades. People just trying to save a dime, and solve a current task. As I noticed, most of the security companies work like "do and run", they take a current project, make some profit and don't think about further support and development of the client's infrastructure.
You have 4MP now and in 5-10 years they'll want 20MP or 50MP cameras with a huge resolution and required bandwidth. So, you have to design your network thinking about future speeds, not 1 gbps or 2 gbps which you can utilize today. Just use cat5e for your endpoints, have your access level switches with 10GB SFP ports (Ubiquiti 48-port can do that, I think) but you can use 1GB SFP's to save some money for now. Use some big, reliable (maybe cisco, juniper, etc.) switch in 2n or 2(n+1) redundancy scheme for your distribution/core level. Or just go with Ubiquiti, to be consistent. They seem to be not bad. Read about STP, you'll need it for access-distribution layer connections. There's the whole bunch of youtube how-to videos about ubiquiti configuration.
I don't think you need QoS or VLANs, the only advanced network technology would be STP (actually, RSTP).
For a big network like that, I'd definitely use some NMS. Ubiquiti has some linux-based soft in a beta status but I've never tried that. PRTG is really good.