Yes bevel everycrack down and out so its a little lower than the good areas around it, so when you fill it and sand it down its all even. Mine looked like Vs but curved way out at the tops. I took out bad foam but it didnt go very deep until the foam changed color into good foam.
If there are any pinholes left in the bumper repair after you sand it down, fill them again or else they will show up when you spray the bed liner on. The bed liner wont fill them.
After all your sanding is done wipe the whole thing down with Wax and grease remover before spraying the liner on.
The dash still looks like when I finished it, still holding up fine. I got a tech fabric dash cover(looks better than the carpet ones) off of ebay to put on the top, just to keep heat off of it.