Timing and length of 'author response phase'
It's still relatively rare for conferences to have an author response period at all, and when it happens, it's typically very different from the response to a journal submission.

For a journal, you are expected to submit a revised version explaining how you've changed things to deal with reviewer criticism. For a conference, on the other hand, the author response period is typically more an opportunity for quality control on reviewers, in which the authors get a chance to say things like: "Reviewer #3 claims that this paper should be rejected because we didn't do experiments, which we find confusing because several key experiments are presented on pages 4-5."  The program chairs then use this review/rebuttal pairing to make decisions on which papers will be accepted and whether they will need shepherding to ensure quality of the camera-ready (for those conferences that use shepherding).

As such, the response time is typically quite short, often only around a week, and typically happens not long before decisions are scheduled to be sent.