@GigaTron,
If you're new to Unity, then I strongly suggest getting grips with how you'd code games in Unity. Coding for 2D Toolkit isn't much different to coding any other game type in Unity. If you're used to another engine, etc, then the concepts in Unity may be a bit alien to you.
There isn't an evaluation version as the product is distributed as source code, making it hard if not impossible to provide evaluations.
@Pfaeff,
It works fine with free versions of Unity, no restrictions or limitations.