Epimorphisms and monomorphisms in the categories of Hopf algebras

Question

From this paper I learned that in the category $\operatorname{HopfAlg}$ of Hopf algebras over a field $k$ epimorphisms are not necessary surjective and monomorphisms are not necessary injective. Can anybody recommend me a text (or texts) where the properties of this category are discussed in more detail? And the same about the category $\operatorname{FinHopfAlg}$ of finite dimensional Hopf algebras over $k$. I suppose in $\operatorname{FinHopfAlg}$ the same is not true, is it? And, for example, is it true that each morphism $\varphi:H\to G$ in these categories can be represented as a composition $$ \varphi=\mu\circ\varepsilon, $$ where $\mu$ is a monomorphism, and $\varepsilon$ and epimorphism?