Fanatic, to answer your question......
Free powers, like ones listed in a unit entry or gained through Chaos focus are generated powers. In "The Rules", under psychic phase, in the section titled "Generating Psychic Powers" they talk about free powers vs random generation. Just to be clear any thing under the title "Generating Psychic Powers" is a generated psychic power.
In Codex: Chaos Space Marines there are two contradicting rules about generation of psychic powers. Under Marks of Chaos it says you have to generate 1 power (notice no "randomly" or rolled) from your patron deities discipline. Under psychic powers it says you must roll for one of your patron deities powers. It also says that Chaos Space Marine Psykers have access to Biomancy, Daemonology, Pyromancy, or Telepathy disciplines.
It's my belief that the chaos focus is intended to fulfill the need to generate the deities power, thus giving the Thousand Sons (unit) Aspiring Sorcerer access to one Biomancy, Daemonology, Pyromancy, or Telepathy power.
So it really comes down to your 4th and 5th options. Also in the 4th option, Codex: Chaos Space Marines says only half of your rolled powers can be from patron deities discipline.
All my info is obtained through digital copies, just in case any one is having a hard time finding it.
Hope this helps.