Even if he had, well water isn't always consistent. Water tables rise and fall resulting in different mineral (or other) content.
I dunno about the metal, but I believe the plastic taste is a classic symptom of chlorine... which I'm sure you already know, having stated that your water was unchlorinated.
The temps seem fine, and I wouldn't worry about a slow start. I would suggest mailing a sample to a water analysis company and reviewing the results.
FYI, sometimes... sometimes a pet store will do a very basic water analysis for you (for their fish tank customers). Doesn't tell you a ton of details, but it might clue you in to the problem.
Out of curiosity... what vessel are you fermenting in?