How the communication between two Ev-3 bricks is done over Bluetooth? What is the nature of data that can be communicated?
You can do it using EV3 Bluetooth blocks. You can send integers, string or boolean using different "mailboxes" so the receiver just need to use the Block to read from a particular mailbox to get the data.
Maybe I write a post where I detail all this more because LEGO documentation isn't helpful at all.
You can use the EV3 bluetooth blocks in the blue tab of the programming software.
One thing though: The two bricks have to have different names. Like "Kim" and "John".
Check the EV3 help too.