Being one with the Force

At the conclusion of ROTS, it seems that the secret of Yoda and Obi-Wan being able to manifest themselves in ROTJ after their deaths lies with Qui-Gon's discovery of immortality...

My question is, if that is the case, how does Anakin learn this "immortality" trick then? He definitely did not learn it from either Yoda or Obi-Wan, so the only possible solutions are that

1) Qui-Gon manifested himself and taught him the skill... (But that seems rather unlikely...)

2) Luke learnt it from Yoda and taught his dad at top speed just before his death... (Highly unlikely...)

3) Anakin discovers the skill himself... (Possible?)

Also, it still does not explain why Qui-Gon's body did not disappear when he died, whereas Yoda's, Obi-Wan's and Anakin's bodies disappeared upon death...

 

Only Yoda and Obi-Wan disappear.

Qui-Qon learnt the secret in death. So why cannot Anakin?

 

Is that so? I was under the impression that Anakin's body disappears as well, leaving the black armor behind...

Could not Qui-Gon have learnt this in life, rather than death? I mean, he was a proponent of the Living Force, while the other Jedi utilises the Sensing Force... Read this in the a book somewhere...

 

If he learnt it in life why does he not tell the council? I think he learns it in death. He "breaks" through to Yoda when Anakin kills the Sand-People. This is the first indication Qui-Qon became one with the force.

 

Well, as Anakin was conceived by Midichlorians, it is possible that they communed the knowledge to him. Plus, being the "chosen one" may have given him an added insight into how to manifest as a spirt.

Or...
[ROTS SPOILER]



...Darth Sidious taught it to him. He indicated that he had learned the secret of immortality from his own mentor.

 

When Darth Vader struck Obi-wan in ANH, Obi Wan vanished. Is it not possible that Vader meditated on this to discover what happened? He had a large gap between ANH and his death in ROTJ to realize the secrets of death.