I would recommend just starting with Apophysis 2.02, then as you become more familiar with the program you will understand more about the other programs and about using the add-ons and freebies.

There are some good tutorials around to get you started.

From the Fractal Forum homepage:
http://market.renderosity.com/%7Efractal/CommunityPage/Links-FracTutorials.htm

Another list of good tutorials:
http://woosie.net/fracfan/viewtopic.php?t=15

The above link is also a good forum for Apophysis help. I get the impression that the folks there are primarily Apo users and they are very nice and quick to help you with any questions you might have.

And as you look at the fractal gallery and see work done in Apophysis that you like, PM the artist. Most are pretty helpful with how they do what they do.