Dave, you need to post pics of her!
Does your fresh water tank have an inspection port? Mine is near the anchor locker. As for ways to drain it, assuming you have an inspection port, you could rig up a manual or electric pump and pump it out. You could get one of those 5 gallon buckets from Home Depot/Lowes/etc., and pump into that (4 gallons at a time!!!) and then dump that overboard. But, honestly, running the fresh water pump may not be the worst thing in the world as it will help you test the system.
The HIN should be on the outside of the starboard transom, just under the rub rail. If you look carefully in this picture, you'll see the lettering right near where the transom intersects the starboard side.