Will ADHD medication help you score higher in your wais?

Yes. This test is heavily dependent on those brain functions that are inefficient in adhd. Often the results from those tests are inaccurate in adhd patients for precisely this reason. So retest while taking medication usually shows improvement. It's the failings of the test.
Maybe. But as this is a test of intelligence, and not attention, the effect will likely be minimal. On medication one might complete the test faster, with less fidgeting, but with a similar end result as with no medication.