Can a child created out of incest have a child of their own? Are they capable of having kids?

Yes. You must be thinking of interspecies hybrids (like mules) which often cannot reproduce. Two people, even though they're closely related, they are the same species. However, because they are closely related, the child may have other health problems.

Chances are that a person born of incest will be fully functional. It takes several generations of incest for medical issues to surface.

Yes, why not?

yes

Yes of course, they are a normal human being!

maybe, maybe not.....