Pick the date you first studied the topic, adjust the interval list if you use a different system, and the planner instantly lists every review date with its weekday and how many days away it is.
These expanding intervals follow the forgetting curve: each review lands just as the memory begins to fade, which forces effortful recall and pushes the next forgetting point further out. Spacing reviews this way retains far more than reading the same material five times in one week.
Yes. You can edit the interval list to match your own system, such as the 2/5/10/21 pattern or a longer set with 60 and 120 day reviews for material you need to keep for a final exam.
Do the missed review as soon as you can and keep the remaining dates as planned rather than restarting. A late review is still far more effective than skipping it, and only a very long gap justifies going back to a shorter interval.