There are belly markers for some morphs such as piebalds. But really you have no way of knowing besides testing him with a plethora or morphs. And it may turn out that he isn't het for anything.
The more likely scenario is he is only poss het for something. Sometimes since there is really no way of knowing breeders will sell poss hets as normals. But thats usually not the case.
As far as breeding results. It depends what you breed him too. If you were to breed him it would only be useful to breed him to a 100% het or visual recessive morph such as albino or piebald.