How do you tell a amle from female of this one - Canadian Tiger Swallowtail? Will females ever puddle?

As for telling gender, the pattern is different in males and females, especially above. It is easier for you to browse images that have the gender identified than to try and describe the differences in detail. However, a couple of more obvious things inlcude the dark pattern that is usually made up of narrower, crisper, and darker stripes on the males; the males have slightly narrower wings; and there is more blue on the upper side of the hind wings of the females. Also, (and this is visible in this photo), the males of Swallowtails (and many other butterflies) have a very obvious pair of claspers at the tip of the abdomen that females lack. They are held side by side at the tip of the abdomen, and on this fellow they are yellow. All male butterflies have these appendages, but in some other groups they are smaller and hidden by "hair", making it sometimes more difficult to tell. The shape and often length of the abdomen is different between males and females too, but that is difficult to quantify, and can vary somewhat with the condition of the specimen.

I also noticed that you mentioned that the underside is visible in this one. That may have been confusing, because except for a very tiny sliver of the edge of the hind wing, otherwise only the upper side is actually visible. So, the run-together row of yellow spots on the front wing below isn't visible, and that is usually a great help in telling Eastern Tigers from Canadian. Since it is the upper side showing, they are separate spots.