[Tanzer]

I've sailed many places over the years. My boat is a USCG documented vessel. You need to displace 10 tons in order to document. Being aboard the vessel (documented or not) in US waters, you are on private property, and thus, you are able to defend it as you would your home. As for foreign ports, documentation provides you with the (supposed) protection of being US property, and thus subject to US regulations.
In MOST waters where piracy may be an issue, you have little to worry about from any government agency EG. Carriean Islands. If you sail to Central American places, well... you're bold to say the least. I haven't done it, but I know some who have sailed to Cuba - just mind the rules.
Little need to worry about dumping anything IMO, but the CG regulations are easliy found - on the web or at any marine store. In fact, You will need to post these regs on a sticker near the head. It is Illegal to dump plastic ANYWHERE.