Reading and modify values from webpage

Hi,

I'm new here and i got some questions...i want to make an project wich includes a thermostat controlled from a web page, and some sensors (presence sensors, proximity) for protecting my home.
I want to know if i make my own webpage could i be able to get the informations from the sensors using the arduino ethernet board?
I would like to be able to modify temperature from the web page, to see the actual temperature and for the presence sensors, to see their status and if they detect any kind of moving, to email me.