Are you getting full or partial overlay doors? If full overlay, then you'll need a backer to nail the crown to, and you'll want it to be finsihed the same as the cabinets so that you can raise the crown slightly to avoid rubbing the door tops if the ceiling is wonky. You can also use it to bring the crown away from the cabinets and overlap the top of the door to give it a more dimensional look. Looks like in the pic that the backer will leave some exposed edge with the crown mouted on the tongue so you will definitely want it to match the cabs. Some crown actually comes with this "backer" pre assembled to it. I find it makes assembly of the joint easier. Cut and assemble the crown on the workbench, set on top of the cabinets and screw up through the tops of the box to attach.
Get the touch up kit. It usually comes with a color matched wax filler, marker, liquid stain and clear coat. Well worth the extra money. One good tip on the wax: rub vigorously to fill the nail hole then use one of the butane torches (the kind that use the cigarette lighter) and sweep the flame quickly over the spot. Then easily wipe away the excess wax.
Use the marker on all of your crown and moulding cuts. Stain the leading edge of the cut before gluing and assembling to hide any bare wood that might peek through.