sunnyside wrote:Anakin was entirely untrained but was supposed to have been able to use the force to aid in his pod racing.
Indeed, he had the superhuman reflexes which are characteristic of an individual strong with the Force. That's an entirely different kettle of fish than making use of a trained Force skill that we've only seen Yoda, Obi-Wan, and Vader/Anakin accomplish successfully and in which Qui-Gon Jinn only began to dabble. Not only is it thusly presented as an extremely demanding skill, it is more basically a
skill, rather than an innate characteristic like young Anakin's reflexes.
sunnyside wrote:In "A new hope (sic)" Luke is able to do a bit and "feel something" in his first shipboard lesson
As he should have, being strong in the Force. That is not nearly the same as saying that he had the ability to use Force powers without training.
sunnyside wrote:and Vader had trouble with him because "the force was strong with this one" indicating efficacy while still untrained.
That line indicated no such thing; in fact it indicated nothing except that Vader could feel that "the Force was strong with this one" - which oddly enough is what the line said. The only thing that gave Vader trouble with Luke in that scene was a couple of pot-shots from the
Falcon at Vader's 5 o'clock high.
sunnyside wrote:Training just lets you pull off much much more. The vanishing act is an advanced way for a skilled force user to will themselves to die. Slipping away while already injured and under physical stress might be what someone untrained could pull off, possibly inadvertantly.
As you say, it is a skill utilized by a trained Force user - as I've indicated above, in fact only three of the best of the best were able to pull it off (if we include Anakin's reappearance as a Force ghost, otherwise only two.) I suppose it's inadvertent use under duress is possible as you say, though such an occurrence is on par with my five-year-old son sitting down to add 2 + 2 and accidentally figuring out the integral of a given interval on the real line. Not really something we could consider a strong possibility.