If your project really requires WiFi, then an Arduino board may not be the best fit. Of course it is possible to add a WiFi shield to achieve this, but that's a really expensive solution.
Take a look at the ESP8266 modules. The ESP8266 is a System On a Chip with WiFi built-in, that can be programmed using the Arduino IDE. There are boards that have more than enough I/O pins for your application, and it can easily host the monitoring webpage itself.
They sell for ~$3 on eBay.