Shower Waterproofing

Just a couple more questions the area I have to work with is exactly 4' by 4' so I'm using a kerdi 4 by 4 shower Pan . my 2 questions are Do I put the curb on top of the Pan or do I butt it up against the side of the Pan and can I cut down the curb And what would be the minimum height off the floor if I can cut it down