Are you referring to explicit Q&A quotes by Jordan, or to Moiraine's belief that she could burn only a few seconds of a thread?

I still don't seee any plausible reason why the DO would have transmigrated Be'lal like the others, but kept that hidden. They all moved unseen for a while, but as soon as Moridin has been named Nae'blis, they all came out in the open.

Taim is Taim, Jordan all but confirmed it explicitely (he's talked of what age Taim was when he slowed etc., explained why he looked older to Rand at first and so on).

Taim was sent to Rand by Demandred, in the hope of playing a role similar to that of Barid Bel Medar at his side, with the eventual betrayal coming much later. When Rand put Taim in charge of the Farm instead of accepting to have Taim follow him around, Demandred saw the opportunity and seized it. Taim was to corrupt Rand's efforts at the BT, working to neutralize its potential and control the training of these men, and most importantly, it provided a perfect cover up for Demandred to recruit male channelers openly... and to reject a lot of recruits with zero potential to join the Shadow (let's just say it's not Taim who went out of his way to recruit men like Logain...).. As we'll discover soon, IMO, Demandred has let Taim keep but a small portion of recruited DF - and possibly all the men who had to be convinced to join the SDhadow, enough to gain control of the BT. Demandred's full army will be bigger than Taim's "faction". Taim won't like one bit his role or status once Demandred moves into the open and establishes his TG HQ at the BT, as soon as the purge is over and Caemlyn is under the Shadow's control.