I agree that Birgitte's knowledge of TAR is a shockingly under-utilized resource, after she becomes Elayne's Warder. For example, when they meet with her in TAR (before she gets ripped into reality) she says that anyone knowingly in TAR sends out "ripples" that she can use to locate them...
In the chapter 'The Wyld' (last page or so of the chapter).
"Tell me how to do what Slayer does," Perrin said, pushing her hand away. "How does he move between worlds?"
"I cannot explain it to you," she said, turning away, "as it is a skill I have never had to learn. I use other methods...
When Gaul and Perrin first go, it is through a gateway. When Perrin learns to jump into TAR in the flesh, he can take others with him (and back out). I can't recall precisely, but doesn't Perrin rescue Faile this way in the aftermath of the battles?
Other dreamwalkers can learn this method, as...