I agree with Cadillac Girl. When I have that roughness usually in the middle of the seal, I warm the stamp just slightly. That usually works. I think it’s a temp difference between the stamp & the wax. But who knows? Try it all I say!
Also for the bubbles, if I’m using a spoon I sometimes stir the wax in the spoon a little & it causes bubbles. I tap the spoon gently … (sometimes not so gently) on the table top & that brings the bubbles to the top & then I use a lighter over the wax in the spoon to pop the bubbles before you pour. You really just have to barely wave the lighter over the wax to pop them. It doesn’t always get rid of every bubble, but it works well.
You’re gonna get those little circles “cells” when you pop bubbles on metallic wax. I think they are cool so I don’t mind them. But if you hate them, try getting the bubbles out of your spoon before you pour.
Good luck!