Nah that doesn't happen - except for first and last. For the other ranks, what matters is how close/far you were from each other in school. So being 1% away from first will get you a better mark than being 10% away from first, even if you were the same rank in the 2 scenarios.
Even then, they still maintain the rank order and so theoretically the difference in marks would be small
Depends on the situation obviously
My understanding is they use a formula to moderate the marks while maintaining the first external mark to the first internally ranked person, the last external mark to the last internally ranked person, and making sure the mean of the internal and external scores will be the same
One of my teachers stresses that the formula takes into account the standard deviation, and hence having a lower standard deviation (everyone close together) will have the effect of moderating everyone slightly higher.
That being said, I still think that internal rank pretty much decides most of it, and the other factors may add or contribute 1 or 2 marks either way at most.