and how 3 is a hardware pin? There is only an output for the LCD.
3 isn't a hardware serial port pin. 0 is. It doesn't matter that there will never be input to the pin from the LCD. The SoftwareSerial instance owns the pin, and will do what it wants with it. That WILL conflict with what the Serial instance does with the pin, screwing up any serial input.
The RFID instance will have similar issues, with one pin being both input and output.
and the magic numbers are beyond me
Perhaps you should see what they correspond to on an ASCII table, then. Perhaps that will prompt you to change them to meaningful values.