Hi!
Kodak Prooifng software come with an open connectivity kit,free of charge, which allows you to submit from a variety of external workflows. It has an easy to use hot folder functionality that allows you to simply drag files into the system and off to the intended proofer. So while it has great integration with Prinergy workshop and the still loved Brisque, you can easily use it with Nexus, Artworks, etc.
The new edition of Kodak Proofing Software, version 5, is coming out at the end of the summer with new features around color control and advances in profile and device link generation. the packaging edition is also coming out in the fall with new connectivity to the epson WT7900.
In terms of the support plans I would suggest you discuss with the Kodak representative as there are several opitions available depending on need.