PCBSD as its name imply is a OS based on FreeBSD. The only difference between FreeBSD and this is that here you many newbie friendly things.
Unlike FreeBSD you don't get just a console to install it and aftr installing you can get desktop.
Ofcourse installing software is also not hair splitting for beginners. They can use pbi to download it.
Also it lastest release is going to be PC-BSD 8.0 (Hubble Edition) which is in RC.
Anyone not knowing anything about unix but is looking for BSD certification should start with it.
Any software that runs on linux will run on FreeBSD through linux binary compatibility layer. You can choose to skip install process of PCBSD and choose FreeBSD instead. Its only advantage then being graphic installer.
Support is through irc and forums and others community based medium.