When a conference has a date for
Rebuttal, does this mean they send the reviews to all submitted papers including accepted papers? Or is it just sent to borderline/rejected papers?
The answer will depend on the conference, but reviews are typically sent to all authors, to give all authors an equal opportunity to respond. At this stage, reviewers might not have seen other reviews, hence, no decisions will have made.
Usually accept/reject decisions are made after the rebuttal phase. All authors get to see the preliminary reviews and respond to them — answer questions or clarify any confusion or errors in reviews. Often it’s pretty clear to authors whether the reviews are favourable or not, even if no official decision has been made yet.