A basic arduino like this: http://viewitem.eim.ebay.pt/UNO-R3-ATMEGA328-ATMEGA16U2-Controller-Board-FOR-ARDUINOs-IDE-Compatible/290901496705/item ? or there is a more basic one?
Concerning the sensors, could I connect them directly to the arlindo board or I need some kind of module?
I was thinking about using this LCD: http://viewitem.eim.ebay.pt/1602-16x2-Character-LCD-Display-Module-HD44780-Controller-Blue-Blacklight-/170817946781/item
It's cheap but I don't know if gonna last...
The second relay will control the power supply, to run the fans.