answer 1
The best ways that I know to keep the knee pads in place are to (a) tape them to you leg at the bottom of the unit (assuming that you wear long pants), or (b) run skate laces through the tabs at the top of the knee pads, and then run this lacing up your leg, under the pants, and attach them somewhere on the pants (buttons for suspenders, through the lacing holes at the crotch, etc.). I've been using option B for years and it works great. You'll have to play with the lace length a bit to make sure that the pads are comfortable yet don't have enough slack to fall down, but once the length is set the pads rarely slide down the leg.