It’s free to all who want to use it.
Some people use the Jtech No Z post processor (on the Jtech website) for laser work. It eliminates any Z commands from the G-code produced.
Vcarve will do a lot. Especially for engraving.
The Pic/xxx Software is worth checking out. You can download demo versions.
PicSender can send very large G-code files which tend to be the norm for raster image work and has the advantage of being seamlessly integrated with my 1.0c and 1.1f.
3.8 should be fine. Don’t expect cutting to be easy. Laser diodes are just not up to the task.