So, it sounds like you have about 100 ppm alkalinity and 5 gal of sparging water? Adding the acid to the sparging water is a good idea in that it helps reduce that tannin extraction potential and it reduces the pH of the wort in the kettle slightly. Both aspects could be an improvement if the sparging and wort pH have been too high in the past. Its a small addition, it won't affect flavor and its good insurance.
Good guesses, Martin. Those are almost exactly what my parameters are.