In my old project we are using Doctrine 1.0.
Now changing to the Doctrine 2.0. What is the difference? now effected on old doctrine queries.
Which php, Apache, mysql versions are supported by Doctrine 2.0?
Doctrine 2.0 changed a lot of stuff. A lot. You'll have to change almost everything related to Doctrine in your project. It's not a painless transition.
As for requirements, you'll need PHP 5.3.0 to run Doctrine 2.
This is a completely new ORM and you will need to learn this new framework without reuse your previous queries and models.
But this is a faster and better structured framework, and I'm sure that is worth.