Mystery number one is who sent Isam to kill the Grey Men sent by Ishamael to kill Nynaeve and Egwene in TSR. Other Grey Men were sent in the same period against Mat and Perrin.

Mystery number two is who sent Isam to the Two Rivers in TSR, and who sent him to kill the BA in Tear (It's Elayne's hypothesis that turns out to be the truth, IMO: they were not killed to be silenced, they were killed to convince the girls that the information they had was true. The person who had the BA killed was the one who wanted to isolate Rand from his friends.)

Mystery number three is who gave the order to Isam to kill Rand in WH. Isam thought it was apparently male chosen careful to hide his identity but not careful to the point of hiding his gender from Isam, but the meeting was in TAR where such things are highly inconclusive.

Mystery number four is who disguised his or herself as Sammael to send a huge army of Shadowspawn to the location where Rand was hiding (the Tairen Manor). This happens in the same scene where it's revealed that Moridin and Lanfear are the two who can easily find ta'veren in the Pattern.

It seems to me the solution to all these mysteries is the same: it was all Lanfear/Cyndane. She's the one who made near systematic use of Isam as assassin. It's especially interesting to note that Isam's patron seems to know a lot about his previous missions....

After what happened in Falme when the three ta'veren were brought together, with the "wonder girls" present, was a pretty impressive exemple of prophecy coming together. Impressive... if you serve the Light, not really a reason for rejoicing when you serve the Shadow.. at least if you serve it loyally rather than put your self-interests first, Lanfear-style. Ishamael's answer to this was to send Grey Men assassins to kill all of those people (but Rand, and Min who didn't count). Lanfear's answer was to try to reproduce the "winning conditions" of Falme to increase the odds of Rand seizing Callandor from Be'lal.

After Falme Lanfear was rightly concerned about Rand's safety, now that the Forsaken, who were finally all free by then, had reasons to perceived Rand as enough of a threat to wish to deal with him now, before he grew stronger (in all the senses).

She tried to build Rand an army of fanatics worshipping the Dragon Reborn as a short step below the Creator, using Masema. Why was this Lanfear? Because who but Lanfear in the Shadow would have taken such a direction, of appearing in dreams as the Creator to someone to make him worship Rand fanatically and gather to him followers - and who would choose for this role the very Shienaran known to have been hostile and a possible danger to Rand because of his obvious Aiel blood?

Then it's obviously Lanfear who sent Rand the dreams about Callandor, the mean by which Rand would be able to face the Forsaken, or at least make them much more cautious to face him. Why wasn't it Be'lal as some think? Because Be'lal wasn't expecting Rand when he came, and admitted candidly his surprise that Rand would show up for Callandor so soon. Be'lal is a careful planner, but his plans were still not much advanced. We know he was promising Tairen a war against Tar Valon, notably. It appears he had a long term plan, in which Mesaana was involved, to capture and control Rand using the "Sad Bracelets". He had gathered 13 Black Sisters (we can see the treacherous side of Mesaana in the fact it's 13 sisters who were pretty much "loose cannons", who had served directly another chosen (Liandrin, agent of Ishamael in TGH) or that could not be trusted or had to be disposed of before the Hall caught them (Liandrin again, who would be exposed whenever the girls returned to TV) that got chosen, and Mesaana added a little surprise by giving orders to the BA to raid the vaults before they left... which exposed them all to the Hall and Amyrlin as BA). Be'lal would have his 13, but they would not be sisters he could use openly where there are AS, nor would he be able to send some back to TV, where he didn't know Mesaana was hiding and controlling the BA.

We know it's Lanfear who passed herself as Else to bring the girls on the trail of the 13 in Tear. In similar ways, she induced Perrin and Mat. It's clearly Lanfear who had short-term plans for the girls and decided to twarth Ishamael's efforts to kill them... sending Isam to kill the Grey Men.

After Rand got Callandor, Lanfear's plan entered a new phase: seduction wasn't enough, she appealed to reason and his need for the two of them to becomes allies. She hatched a plan that would protect Rand for a while longer: she gathered together four Forsaken, with the purported goal of capturing Rand as he attacked Sammael. As they did, the odds were they would choose not to attack Rand. This alliance would also make the trio (Mesaana, Semirhage, Demandred) more cautious to interfere. That left Moghedien - the hated rival in TAR -= who Lanfear didn't forget and painted fancifully as one of those determined to see Rand death ASAP... Moghedien of course didn't even know Rand's name by then! The other side of that plan was that Lanfear could pretend the very opposite to Rand: the threat of the Forsaken attacking was imminent, only through an alliance with her could he stand a chance to win. She told Rand Rahvin sent the DH to Rhuidean. She clearly lied: Rahvin was going along the plan, and even mention Melindrah's role to engineer a false attack on Rand by Sammael if all else failed to bait him to Illian. Those DO were sent by Shai'tan as in eyes to ascertain Asmodean's treason, and if it proved true to kill Asmodean and the two ta'veren.

Lanfear had wanted the girls, Mat and Perrin around to increase the odds of Rand's success in seizing Callandor, but for the next phase of her plan she wanted to clear Rand's entourage to have him to herself. She let the girls interrogate the BA prisoners and tell them about plans. The girls hesitated too much. Lanfear tasked Isam to kill the BA and nail their tongues to the door, to finish to convince them they held valuable information. Lanfear probably didn't care much where they would choose to go hunting BA, she just wanted them to leave Tear to keep hunting BA. She sent Isam to the TR because of rumors of troubles there reaching Rand, who sent Perrin. Isam wonders why he was sent. He was sent to hold Perrin there.

Then we come to the WH efforts by Isam to kill Rand. After her demise, Lanfear has hated Rand and wished him dead very very badly. She's got a huge problem though: Moridin won't have it - he wants Rand alive for now, and he has her mindtrap. Lanfear knows that if Moridin has his way, she'll never get permission to kill Rand, and even if she's allowed to come close to him, she wouldn't survive long if she killed him then. So she had to fall back on attempts to have him killed, attempts she wouldn't be blamed for. To prevent the Cleansing, the Dark One temporarily lifted the order not to touch Rand. He could be killed, if it was necessary to prevent the removal of the Taint... which isn't saying "I want you to kill the Dragon"... as all the Chosen knew. But some would very much have wanted Rand dead. So Lanfear thought the opportunity was good to have Isam try to kill Rand. She passed herself to him as a male Chosen hiding his identity.

Then comes the attempt with the Shadowspawn army. She passed herself as Sammael for this (Myrrdraal can sense the OP in someone... can they differentiate between saidin and saidar... we do not know...). Moridin knows Sammael died beyond the reach of the DO. Lanfear and the others don't. At the meeting where Moridin tried to get to the bottom of it, Cyndane made sure to exonerate herself on purpose by openly showing she hoped Moridin would let her get close to Rand again. She got the expected rebuttal. But that attempt is so unlike Lanfear, who despise using Shadowspawn - and mindtrapped she wouldn't dare anyway? Well, that's exactly what Cyndane hoped Moridin would conclude.

Now comes the more recent developments. It's pretty obvious Moridin, after he revealed to Rand the DO had brought back the dead Forsaken not killed by balefire, and after Rand's epiphany, is the one who decided to use Cyndane against him, appealing to his mercy. We'll see later what Moridin hopes to achieve with this exactly.

I think the meeting with Isam simply reveals that Cyndane is rather unhappy, an euphemism, to be forced to play that role. She wants Rand dead all the more, and the sooner the better.

Do we see Moridin in the Aiel town? I don't think so. I think it was Cyndane under a MoM who wanted Moridin's presence there to be seen by the town and by Isam himself... if he is ever questionned about who gave him the orders to kill Rand, and he can't find his patron among the Chosen, Isam will have seen Moridin in that town... She then appeared to Isam as a woman (no way to tell for sure if she did it under her real appearance or not.. I suspect it was not) but she spoke to him with the apparent authority of the Nae'blis, told him he didn't have to obey the orders of the other Forsaken, unless the DO himself countermanded the mission she was giving him to kill Rand. It's high risk, but I see a possible sign Cyndane is getting really desperate to see Rand dead. She probably loathes the role Moridin has in store for her, and let's not forget that beside the fact she hates Rand with passion, having him killed so close to Moridin's goal is also a way for her to get back at Moridin, whom she probably hates about as much as she does Rand.