"what should naruto have learned over the past 3 years?"
well konoha also uses wood techiniques, so maybe a wood technique wood be appropriate for naruto because sasuke indeed already makes use of the fire element. It doesnt have to be completely a wood technique, maybe something that supports his other skills. ANother jutsu idea:
kawarimi no kage bunshin - basically a kage bunshin that upon being hit produces a crappy log giving the impression of kawarimi. Makes no sense? Well, it may be used as a confusion tactic, rendering the enemy unable to determine whether the guy he hit was a clone or the real one and just used kawarimi. NOt so useful? Well, maybe it can be used like how sasuke used kawarimi by attaching an explosive to the wood. Naruto can attach a long fuse explosive to some of his kawarimi no kage bunshins and let it serve as either a trap counter or suicide attack strategy.
