There is a Duane Reade, a Walgreen's equivalent, right in Times Square. In fact you can't swing a dead cat without hitting a Duane Reade in NYC.

You'll be fine.
I picked up a free subway map if you'd like me to mail it to you. I can also pick up different brochures. The internet is a wonderful thing but sometimes I like the paper in my hand. But I'm old.
As for the CP Zoo, I can't imagine anything more than a couple of hours. It's more of a nice distraction and a wonderful stop in the Park. CP is amazing.