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: Bourbon Barrel Imperial Stout
On Deck: German Lager