Do they have beer stands?

Technically there are no beer "stands" except for special events such as adults nights. However, Park Place Café, Bird's Eye Bar & Grill and the Patio at Café Brauer (technically just outside the zoo gates) do sell alcohol, including beer. The latter has by far the best selection of craft beers.

Yes, yes and yes

All you could've want

The cafe there sells beer

Yes.

As far as I know, the cafe in the zoo has alcohol