Seeeduino upgraded to Atmega 328

I'm just about to get my first setup, easy question for you:

Can I use these all at the same time:
Seeeduino Mega
XBee Shield V1.1
XBee Pro ZB
LCD 16x2 for sale at seeedstudio

I will communicate between this combo-device and an Atmel AZ USBStick.

Eventually I would like to put the Atmel Zigbee BitCloud stack on the ATMega328 with the '231 transceiver.

Also, is there a distributor in the US?

Thanks,
Ray