Seconds/years are man-made units.
If two things can happen simultaneously AND independently from each other is time is a vector not a plane?
You wouldn't be AWARE if time was flowing backwards. The Big Bang (I mean Crunch) is yet to happen!
Yes but time itself is not manmade. And it comes in different sized intervals. That's all you need to prove its discrete using the information content argument.
If two things can happen simultaneously AND independently... But a dimension supports that perfectly well.
I don't think it matters which direction time flows; my arguments are symmetric and independent of the flow of time. A circle works whatever the direction of time is.