The contraposition law states that a conditional statement ($\phi \rightarrow \psi)$ is logically equivalent to the inverse ($\psi \rightarrow \phi$) of its converse ($\neg \phi \rightarrow \neg \psi$). Symbolically, the law states that the following holds for every interpretation:
$\vDash (\phi \rightarrow \psi) \leftrightarrow (\neg \psi \rightarrow \neg \phi)$
Now if what you mean by "multiple contrapositives" is the fact that contrapositives can be successivelly iterated, your answer is yes, so that the following holds:
$\vDash (\neg \psi \rightarrow \neg \phi) \leftrightarrow (\neg (\neg \phi) \rightarrow \neg (\neg \psi))$
Recall that the Greek letters $\phi$ and $\psi$ in the above statements are actually not part of the language, but just metavariables, as they stand for any well-formed formula of the language L of our statments (This also answers your second question with a yes). Then the successive iteration of contrapositive comes easily.
(Note however, that in classic logic they are superfluous: $\vDash \neg \neg \phi \leftrightarrow \phi$ so that the successive negation can be eliminated)