Definitely not! We currently plan to fully support Zend Framework 1 until at least early 2014, including maintenance and security updates.
Absolutely. An important part of Zend Framework 2 is the migration layer that will allow ZF 1 code to run on the new ZF 2 engine, which will be made available once the ZF 2 APIs are finalized. With it, you will be able to add new ZF 2 code, and refactor existing code, at a controlled pace.
If the project will complete mid-2012 or later, start using Zend Framework 2! The current beta 3 is a great opportunity to begin acquainting yourself with the main features, and the feature-complete beta 4 and GA releases will follow quickly.
Zend Framework 2 is based on PHP 5.3. We expect to add support for PHP 5.4 once it starts to be adopted by the PHP community.
You can download the latest build from http://packages.zendframework.com. You can also get more information about the Zend Framework 2 project at http://framework.zend.com/zf2/.