Regarding power consumption - it relates to how busy the wifi chip will be.
As a point of example, a rig I have with a WiFly with a 3mA battery 100% uptime and a few sensors ... lasts just under 2 days.
With it in a sleep mode for all but 30 seconds out of 5 minutes, the lifetime extends to weeks.
A link to more links: http://arduino.cc/forum/index.php/topic,56724.0.html
Not certain if this fits your specific project needs directly though. Are each of your sensors DIRECTLY connected to the Arduino, or are they remote from the Arduino? Is your display separate from the sensor/data collection unit?