Research on Reading

Dear friends
I am conducting a research on reader response. I am adopting a qualitative research method . It is an exploratory research in which I am trying to explore how students whose native language is Arabic and who are enrolled in English language department respond to metaphysical poetry written in English. I have a problem concerning sampling and I would really like to have your comments on that.
First : is there a problem in exploring the responses of students who volunteered to read and register their responses in questionnaires or through interviews. I mean if students chose to participate and it was not possible to select them randomly.
Second: Must students be divided into males and females equally. I mean is there a problem if most of students were males or vice versa.
Third: how many poems do you think would be sufficient for measuring their responses?

I would really appreciate your comments and personal contact on this issue .If you like to discuss that with me on chat please add me to you chat list on yahoo :[contact details removed - please add them to your profile]
Thnak you