Crazy?

Why does Semirhage keep prisoners alive when it is likely they will escape, and Compulsion or a circle with Myrdraal can induce their defection for effectively? Why did Rahvin keep Alteima around, when she made it likely that word would get back to Morgase, whom he knew to be imperfectly Compelled? In each of these cases, it was because they had other agendas beyond winning the fight. Ishamael had his reasons too, and ego was not least among them. Moghedian confronted Nynaeve in T'A'R, where Nynaeve beat her in a way she could not have in the real world. Rahvin lured Rand into T'A'R where Nynaeve could provide the critical distraction to help Rand beat him. Semirhage attacked Rand who was accompanied by the strongest normal sister alive, and Forsaken-level woman and his strongest male channelers, and no links on her side. Osen'gar tried sneaking up on primitive people in the wilderness, Mesaana took on a natural T'A'R expert on her own ground, with allies who had Forsaken-level skills, and no competent allies of her own. In each situation, the fights they initiated caused their defeat, when they themselves had chosen the terms of the fight. That a tactic failed does not make the Forsaken stupid for picking it - it just makes it par for the course. Also, bear in mind, Ishamael came back from his wound. Maybe that had something to do with the way he chose to confront Rand. And of course, he never wanted to kill Rand, until pushed to desperation. As his game scene reveals, he believes that he needs Rand alive and on his side to achieve the optimal victory from his point of view.

Psychology. If he can beat Rand down physically and overwhelm his HotH (remember the link between the battles - if Ishamael beat Rand, the Seanchan would have won), then it is easier to convince Rand that resistance is futile. As I said, he was probably entirely using the TP at that point. Maybe, given its nature and the way we see it work, it can't be used to capture Rand harmlessly, or shield him without doing some sort of damage. The point is, there are all sorts of possibilities. These are just things that come off the top of my head, and given our incomplete understanding of the mechanics of that fight, assuming he was being stupid is short-sighted and unsupported.

Those only matter if you are deliberately trying to change something. The status quo is default,, which is why they walk instead of drifting or teleporting. They walk because they believe they should. T'A'R is a place entirely of the mind, and they have no physical bodies, so there is no need to use muscle-memory locomotion to move about T'A'R, but everyone does it because that's how they think it should be. If Rand believes all he has to do is resist and defy the Dark One, that might be enough by T'A'R rules. Also, if he's aiming at the Dark One, that might give him enough will-power heft to easily resist a mere human. Like heaving a bag you think is full, only to find it's relatively empty or light. He's geared up to resist a near-omnipotent deity, so a Forsaken is much easier than expected.
Finally, as I said, all previous and most subsequent contact with Ba'alzamon was outside the physical world. Maybe he pulled Rand into the pseudo-dream or joined him in the Horn-created dream because that was the only way he COULD reach Rand while the latter was awake. We don't know the mechanics of his entrapment, only that he was still only flickering in one known recent appearance in the real world away from Shayol Ghul (Fain's experience near Shadar Logoth). Maybe he even knew the attempt was doomed, but took a long chance. Certainly Rand and company have willingly gone into fights with similarly slim chances of success because it was necessary. Unlike the other Forsaken, Ishamael seems to be a true believer and might actually be the sort to put his ass on the line for the Shadow if he thought it necessary. With the good guys about to put the smackdown on the Seanchan invaders and win another year of peace for the wetlands, maybe he felt he could not let this pass unanswered and did whatever he could to try to beat Rand down.

Another option, given the link between the battles is that maybe the Horn prevented channeling because it (or the Pattern or whatever made the battles linked) necessitated a fair fight. The unkillable, power-immune HotH against a mortal army should not have been capable of being driven back, but they retreated before the Seanchan whenever Ba'alzamon drove Rand back. With that kind of absurd governing mechanic, maybe the Power of the Seanchan's champion was also curtailed, as they were unable to effectively use it against the HotH.

The way he did at the end of tDR? T'A'R seems to be one of those situations where ignorance is bliss. He deflected balefire, because he assumed with all the Power flowing into him from Callandor that it was possible, without knowing that not even Callandor should be able to do that. If Rand believed that Ba'alzamon could not do whatever manipulation he was attempting, than maybe it was so.

And the surest path to victory for the Shadow might seem to be the destruction of the Dragon, who is humanity's one chance for survival, but he plainly does not want that. Ishamael shows that he is the sort to risk defeat for a chance at a greater victory, so for any number of reasons, he could have been doing the same at Falme, if for no other reason than to shake the confidence of the Sounder of the Horn and not let him believe having that talisman makes him invincible and thus have no need to give in to Ba'alzamon.

Well neither is the Horn.

Warder bond. See above, re: surviving injuries. And why would the woman of Sidious' dreams bother with extra effort on a non-channeler, beyond a perfunctory slap to get him out of her way?

A swat of Air would probably take less effort than an all out effort to crush him. On the scale of the Power she had at her disposal, that blow that struck him was probably no more than a rabbit-punch, and no more than he rated. Plus, he contributed nothing to the fight, so you can hardly criticize her choice. Had she beat Rand, Lan, nor anyone else, would not have lasted long. She had no interest in anyone other than Rand and his possible paramours, and was not even thinking clearly enough to recognize or distinguish between two women whose names she had to have learned while traveling with them, nor did she have sufficient strength to bother with them or anyone else once Rand came at her.

Me either, but this was hardly one of those instances. If he blundered at all it is in the idea that the scene was inevitable, since he was so fixed on building up Moiraine's sacrifice that he had to make going to the docks and her own doom all her notion. If she had not insisted, Rand would not have gone, and Moiraine's whole plan would have failed. He needed Moiraine out of the way to let Rand grow without her, and he needed her to come back as a hero, so he forced the circumstances of his disappearance. Given all that, if he could really not think of any realistic way for Lan to survive to do...well, nothing significant that anyone else could not have done...he could have had Moiraine tell him to stay behind or fetch this, that, or the other thing, or even to secure the Traveling ground or something. He didn't need to have Lan present when Lanfear attacked, so there was no need to 'force' a 'contrived' survival scenario. That latter was entirely plausible, especially as we have seen Lanfear use the Power as her 'hands' on other occasions where she is pissed (Asmodean in Rhuidean, for one). She was not crushing a dangerous foe when she hit Lan, she was batting away a gnat, and put no more english on her blow than she needed to send him flying, without caring if he broke his neck or not (and NS reveals that he knows how to survive such a fall or crash).