yeah just make sure you use a primer to suit the type of paint you will be using.
As for the bumper, theres 4 bolts in the boot, 2 on each side, undo these, undo the 6 mudflap screws and slide the bumper backwards. Prices, anywhere from $60-$100 for a good example me would thinks.
The fuel tank is held up by two straps, the bolts are under the car