I think we can trust Cadsu. She really wants Rand to stay alive and free. She mentions several times what a mess "some" AS have done when they kidnapped Rand. Also her promise (made in PoD, chap. 27, p.539) seems to be free of any of the usual loopholes made by AS. I quote "whatever she'll do, it will be for his (Rand) own good, not her own good, not the good of the White Tower".

About what she's going to teach I agree with what has generally been said. She's going to teach Rand and the Asha'Man how to work with AS, and possibly the necessity to be bonded. Being bonded is probably one way or the way to hold off madness. In the CoS, chap, 33, it is said - about Rand - that the sense of Alanna is a comfort. Also from what is said in the Glossary, I think Cadsu has bonded several men who could channel and found out that it was slowing the madness process. Also, what Elyas says to Perrin, although it is not to do with the Power but only madness, the bond prevents Elyas from becoming crazy (pp.223).What I found also interesting is that Cadsu does not seem afraid of the Asha'Man and if she does not completely trust them, at least she respects them (Chap.33 and 41, POD) and I even believe she has started her teaching during Rand's healing from Padan Fain's wound. She says "each one has done a part, including some things I think have not been done since the Breaking" (p. 713). Surely she means men who can channel working with AS.

A second part of her teaching is teaching them to be human. Several hints, as p.279, "he has forgotten how to laugh. Unless he finds laughter and tears again, the world faces disaster. He must learn that even the Dragon Reborn is flesh". It is also obvious that when Rand is with Min, he is more like good old Rand and feels better. I would also dare say that RJ being such a romantic fool that it would not be a surprise if in the end Love will save Rand and the world.