1) buy a 120 volt AC unit, purchase an inverter to operate it off 12 volts DC. Inverter should be sized to be able to run TV, DVD player and a possibility of a satellite receiver.
2) On your own. You need to check what kind of cabling exists as a color setup may not work with what is there.
3) you need to measure the sets you like. It should be able to be left in compartment. I would wrap it in a shipping blanket to be extra protective
4) good quality gravel about 4-6 inches thick should do. Make sure it drains water away. 3/4 inch minus placed over 1 1/4 minus
5) refer shelves show up on Amazon and ebay. You need to locate your make and model.
6) using a steam cleaner type vacuum on the shades clean them and the left over moisture allows some to be reshaped. Make sure they dry fairly quickly or you will be fighting mold.