RFID and 3G + GPS


I need to monitor where (GPS) some people use an RFID card and obtain this Information via GSM / GPRS ..

I thought:

3g + GPS shield: Cooking Hacks - Electronic and IoT Kits, tutorials and guides for Makers and Education
grove 125khz rfid reader

But ..

Is this possible? This shield allows me use I2C ports of Arduino?
I see it communicates RX / TX (UART) ... pin 2 to 13 and A0 to A5 are free ?


thank you