Brett, I have never worked with zebrawood before, but smooth on has worked very well for the few bows I have made. Bubbles are caused by 1-not enough smooth on and 2-not enough pressure. Put plenty of smooth on on the bow, don't try to skimp. Whatever pressure system you are using, make sure it works properly. I doubt you will have a single air bubble...I never have.
As for the zebra wood part of the question, I'll let others chime in. But I think the smooth on should fill the grain nicely. And you don't want the wood or glass perfectly smooth anyway, so the epoxy has something to grab.
Dan