I think your best best for original graphics is Viper Customs at http://vipercustoms.com .
You should be fine in terms of the salt water investigation since you're taking an expert with you. You can take off any existing stripes with a heat gun or with a magic eraser. Mine were so baked on that I had to use the eraser. Its a rubber wheel that you put on your drill and it buffs the stripe off. Very easy and effective. Once you have the stripes off and the hull buffed, you can add stripes back. This is done with stickers/decals. The only way to paint a boat is with gelcoat and this is expensive and must be done by professionals. But you can restripe the boat with decals by yourself. You can find the magic eraser on eBay or Amazon. Hope that helps. Good luck on the boat purchase.