The top 150 figure is a good estimation, but it isn't a general rule. In my batch there are 250 students (All faculties) and in the latest one, there are around 400 (all faculties again). A lot of people leave for UET after their admission here. So the merit does drop changing from year to year.
Nope, never heard of anyone. Plus I don't think that the topic might have come up in any casual conversation.