2007 Jeep Cherokee "Dog Damage"

Question:

Own a 2007 Jeep Grand Cherokee.
My dog chewed through the:
Front Right Passenger Seatbelt,
Rear Left Passenger Seatbelt, and
The wiring to the rear hatchback door (electric locks will not disengage for the door or window, I believe the wiper motor and perhaps the deice is inop too).

Are these components relatively easy to replace?
Can I do it myself?
If a dealer or mechanic does it what would the approximate cost be?