Jon, I had the same problem and went through similar steps to repair it as well. I put in an new battery within a year of buying the car and it wasn't like that when I put th new battery in. What I found was that the battery tender that I kept on it was causing just enough acid to weep out and create the corrosion. Since cleaning up the mess and removing the battery tender, I have not had any more problem with it and I do check it every week now........paranoid!

And, I too have yet to figure out what that vacuum line goes to but I repaired it by sliding a rubber vacuum hose over the split ends (which just happended to be the perfect size to seal). I have yet to find anything that does, or does not work with the line open or closed.