How would be 'Do you know Rosa?'
Do you know Rosa? = هَل تَعْرِفين روزا؟
Why the oh rosa?
Is asking Rosa if she knows something, not asking someone else if she knows Rosa.
Is there a fatHa missing in تَعْرِفين? The speaker is addressing a woman.
Yes, I think so as well. In MSA the ending should be -ina? Could a native confirm?
They need a comma for the English to be correct.
Or an -it- after the verb.
why ta3refeen instead of ta3ref
Because you are addressing a woman. It is the feminine form.