The kneelers do have padding, I'll use some thin masonite with foam, then covered with vinyl. They'll attach to the rail via velcro strips so they can be removed for cleaning and repair.
For the height, a went around to several pieces of furniture in the house till I found something close, measured from the floor, then added two inches. I'm 5'10" and it is a little bit of a stretch for me to the height I came up with, which felt about the same for a prayer rail at another Church. π The minister asked the same thing, and laughed when she pictured my wife (5'2") and I going around the kneeling in front of different pieces of furniture.