There are a couple of functions restricted to DAZ PA's currently, but the majority of content creation tools are free and included with DS 4.12.

What's not included in the box:

Functions Restricted to DAZ PA's include:

Conversion of strand base hair to Dynamic hair.

Importing High Definition Morphs (This function allows sculpting on higher levels of subdivision in 3rd party apps and loading as a morph onto a base figure.)

What's not free

Most 3rd Party content and plugins.

The majority of Daz 3D or Daz 0 content. Base figures and a stack of other content are currently free.

...

Documentation

One thing to keep in mind as far as documentation goes is that it tends to come in levels, from a range of sources. With the fairly rapid development of Daz Studio's functionality the creation of an all encompassing manual has become a practical impossibility. Daz 3D does have quite a bit of info on there information centre page, but some of it is outdated and it doesn't cover every aspect of the software. http://docs.daz3d.com/doku.php/public/software/dazstudio/start

What you will find is:

General user and basic functionality: Highly documented with online documentation and supporting Youtube videos and tutorials. Daz Studio also has a Lesson mode for some basic tutorials.

Intermediate user and functionality: Pretty well documented with online documentation, tutorials and supporting Youtube videos

Advanced user and functionality: Somewhat documented with some online documentation and tutorials(Some already a little outdated) and some paid tutorials alongside Youtube videos and 3rd party sites offering guides/tuts. Forums are also a good place to find info with advanced technical issues.

Emerging functionality: Forums are the best place to glean information about newly added functionality especially change logs and public Beta threads, where new functions are explored and tested before widespread public release. New functions are generally introduced in videos by Daz 3D, but generally don't go into a great deal of detail as to what this or that widget does but give a general overview of the new function. Tutorials and more detailed videos generally emerge as time progresses.

Some good introductory reference material: This covers most of the new features introduced alongside of the Iray engine in DS 4.8. http://docs.daz3d.com/doku.php/public/software/dazstudio/4/new_features/4_8/start

This covers the new surface settings using the Daz Iray Uber Shader http://docs.daz3d.com/doku.php/public/software/dazstudio/4/referenceguide/interface/panes/surfaces/shaders/iray_uber_shader/shader_general_concepts/start

The Daz 3D Youtube channel also has a lot of tutorial and introduction videos. https://www.youtube.com/user/WWWDAZ3DCOM