DB and EA AT commands in XBee pro s2b

I use some XBee PRO S2B modules in API mode and I want to run some diagnostics using the above AT commands:

[li] EA[/li]In the latest manual ( Xbee manual 2013 ) there is no reference to this command that returns the ACK failures.
When I send the corresponding AT command frame,the module responds with an AT command response frame with command status OK (not error or invalid command). Also, after running some tests I realised that the returned values were correct.
Q1: Does anyone know if it is OK using this command? And why it is not included in the manual? It is deprecated or what?

[li] DB[/li]According to the manual this command returns the received signal strength (RSSI) of the last received RF data packet (this includes APS acks).
Q2: In the case where I measure the RSSI in a module that runs as router, as “last received RF data packet” can be considered only packets that are destined to this module or this term includes the packets that are destined to other modules but are routed from this module? i.e the value returned from “DB” changes when a packet is received in the application layer (APS) or in the MAC/NWK layers?

-Also, while the two modules where I run my tests have the same firmware (0x23A7) and the same power settings (Power Level and Power Mode), I get quiet different values for the RSSI at exactly the same contidions. I tried interchanging their PCB antennas but I keep taking the same results.
Q3: Has anyone encountered the same problem? Any ideas of the reason this is happening would be appreciated.