CATIA Version 5 is the latest version of CATIA. fully redesigned it is a completely new product.

CATIA V5 is shipped with different configurations so it's hardly possible to say it does this or that because it is so much dependant on the options. This is why we say 'can'.

CATIA V5 can read CATIA V4 files. It will not be loaded directly inside V5 database but merely viewed inside the general framework.

There is an API to work on CATIA V5 files: CAA.