This licensing FAQ is one of the good reads to understand issues related to GPL, when and how software can be combined etc. - particularly when you are integrating between different licenses such as Apache's and GPL'ed softwares.
've roughly organized the questions by topic: they start out discussing the drafting process, move on to the more significant changes in draft 3 such as lockdown and patent terms, and then more specific, nitty-gritty questions. I've also done some slight