The version of Python needed by cvs2svn is documented in the requirements section of the cvs2svn documentation:
Python 2, version 2.4 or later. See http://www.python.org/. (cvs2svn does not work with Python 3.x.)
The same section also describes some other requirements that you will need.
The Python interpreter can be placed in your PATH, or alternatively you can invoke cvs2svn using an explicit python interpreter like
/path/to/my/python /path/to/my/cvs2svn [args]
The rest of your questions are not about cvs2svn but rather about how to install a working Python on your platform, which you haven't even specified.