This project has been aborted for now, as I have found an open source library called NTL that is an absolutely outstanding C++ library for not just simple arithmetic on arbitrarily large integers but also has support for vectors and matrices over integers and finite fields already built in. I highly recommend it if you are looking for a library in C++ as it is very easy to use and very well documented in my opinion.

NTL is written by Victor Shoup and is hosted on his site ...

http://www.shoup.net/ntl/index.html