And answering your second question, no, by top I mean actual height in relation to the sea. My idea is that plate 2 violently crashed with 1, and actually got a big part of it sliding on top of it. Do you think that's a bit too much?
Not really. There is a plate that slides under the other but that does not really mean the other plate is higher. What happens is as the plate slides under, there is a lot of friction/resistance with the contact of the other plate. That friction makes the plate "on top" fold and the land to rise over time creating mountains and plateaus. But yea, I guess it's pretty much the same as saying that it's higher.