I'm suspecting that the "Tahiti is magical" is something they've implanted for healing or activation... If you want further rumor-thoughts (anyone), PM me & I'll respond, to not ruin things for others.

Reliable public sources (incl Joss W) have said by end of season 1, we'll know how Coulson came back.

Personally, I doubt it'll have anything to do w/ Wanda. Which would be ironic as the celloist he was dating in IM2 was named Wanda, and Wanda Maximov/Scarlet Witch has been noted to play cello (or at least strings)