Wireless data exchange up to 2 bytes/s
No. RFID is very much a master-slave relationship, in which the master (the RFID reader) supplies both power and timing to the slave (the RFID chip).

There's simply no way for two masters or two slaves to communicate directly with each other.

For such a short distance, optical communication would make the most sense. IR transceivers are commonly available and inexpensive, but I don't know if there are any Arduino-specific boards that incorporate them.