Cider will ferment out completely dry since it is primarily simple sugar. I would put off any acid additions until after fermentation is complete. Dry cider should have no residual sweetness. You can't judge the finished ciders acidity very well by sampling the unfermented apple juice.
Something is always fermenting....
"It's Bahl Hornin'"
Kegged: Sour Saison, Pale Ale, Aggie Ale, Firestone DBA, De Koninck Blonde
Bottled: Belgian Quad (Grand Reserve), Derangement (Belgian Dark Strong)
On Deck: Pliny the Younger