On all breakpoints, the Product Page carousel is really lacking. There are no arrows for the user to click or touch, and the circle indicators are tiny! How can we put arrows on either side of the image and/or increase the size of the circle indicators?

for this I could suggest to use all images with the same ratio (pre-uploaded) or use such preset at Crop Resizing and 4:3 ratio, so everything will be in one level
we can see what you are referring to, and at this point I'm sorry to say this, but it will be the feature request, not the one we discussed in the other thread, but here is the link to vote for it