We should not be teaching blindly following an absolute in any science. There is always doubt, and if counter evidence exists it should be presented not swept under the rug because a majority disagree.
Equal time? No. Should it be discussed? Absolutely yes.
No, it shouldn't be, in the context of studying science.
Creationism has no more validity than any other creation myth. It should be dismissed from science as readily as Zeus, Ra, or Xenu.
The appropriate place to study mythology is in a mythology class - until and unless that mythology offers falsifiable evidence to support moving it into the sphere of reality.
Equal time? No. Should it be discussed? Absolutely yes.