If your question is does compliance affect relapse (SVR) the answer is "yes" . Different studies deal with this in different ways in terms of reporting. In fact, some studies specifically deal with the subject, for example the 80/80 rule studies.
I don't think so. I think all that is required for it to be considered a relapse is that you reach UND, usually by at least week 24, and then stay UND until EOT.