Do you know how did he find out that the EEPROM address was 0x50?
There is an I2C scanner sketch floating around. It queries all the addresses possible, to see which one(s) respond. If there is only one I2C device connected, the address that excites the scanner code must be the address that the device has.
In my understanding it is because by default line 8 and 5 are at one. Am I correct?
I'm not even able to guess at what you are talking about, so I'd have to say no, you aren't.