Setting up Bitcoin Miner in a data center
Yes. I definitely wouldn't take the chance. Minimum is a possibility of a DoS attack. I'm not familiar with the Antminer firmware and how that's setup, but you could possibly get hacked in your WebUI. Then they could point your miner at their pool.
Yes, a firewall with VPN capabilities and a switch are your typical data center networking setups. You don't really need to set it up that way. You could use a simple home router and turn the WiFi off. Then attach your Antminers to the router. If the router has VPN capabilities, then use that. Otherwise you can setup a computer in the data center to with TeamViewer or LogMeIn. Then you can remotely access your devices through that.