I pre-purchase general admission tickets, does anyone know if that gives access to the witch exhibit as well?

You'll need to add the exhibition ticket to your cart on top of the GA ticket. It's a timed ticket, so you have to picked a timed slot.

You have to pick times for each show.

It includes the Witch exhibit, however a side note that you have to choose times to enter the museum and the exhibits inside and provide negative covid 19 testing if you are not from one of the low risk states.

Yes it does. Only exhibit that's EXTRA is the Chinese home