New to Arduino , need some guidance on school project

We are trying to integrate some sensors and use the arduino board to communicate with an Android Phone/Tablet wirelessly.

I do not know what board I should go with, either the Uno or the Mega board? Also, I think I should use the XBee Wifi module … do I need some type of shield to go with the module?

If this is the correct set up will the Wifi module/Arduino connect directly over the wireless LAN or would I have better results going through internet actions?

Any and ALL guidance is welcome!


A google search like below can provide some previous post.