A: Both are OK, but Left is usually preferable, because it matches "Katie told me" (which was not "Katie had told me", which would be unnecessarily verbose). Exception being, if you want to emphasise "had" as opposed to "had not" which someone else may have claimed - in such a rare case, Right would then be best.
B Both are OK, about equal.
C & D: Both are OK but Right is a bit clearer. If you change "in 2000" to "in the year 2000" to make it a bit clearer that you're talking about a year, and a past event, then Left becomes equal good.