I looked up that thermostat and it SHOULD be z-wave compatible, so you should add it as a z-wave thermostat.
The thermostat is also software upgradable, so go to its manufacturer's website and download the software. You use an SD card to load the software onto the thermostat.
As far as Z-Wave vs WiFi, the two are very different. Z-Wave is a protocol expressly designed for home control. So when you add a thermostat the thermostat just says "Hi, I'm a thermostat" and Vera immediately knows how to talk to it.
WiFi on the other hand is a generic networking technology. You can run almost any sort of signalling over WiFi, and there isn't really a standard way for things like lights and thermostats to communicate over WiFi.
Some thermostats (such as NEST) have plugins written, the plugin knows how to speak that thermostat's particular language and can talk to it over WiFi. However without such a plugin, Vera will not generally control WiFi devices.