Attiny communication with arduino through xbee radio

Hi
I am new here. My project is to deploy attiny which will manage pir detector, temperature sensor and magnetic door detector everywhere in my house .

An arduino will be the master of these attiny(s) circuits.

I want to be able to communication between attiny(s) and arduino with xbee s2 radio.

My questions:
1/ do i need attiny45 or attiny2313 to able to speak xbee ?
2/ i need an hardware example on the tiny side to start ? Have you got an example?
3/ i need a attiny example program to start (i will use arduino ide) have you got an example to start?
Your help will be great for me to start... Thanks
Be