The books never said she looked like a teenager. They only said she looked much younger than she did before her stilling. I always took this to mean early to mid 20’s instead of early to mid 30’s like I pictured the aes sedai. As far as the elayne story, thom was just as disgusted as you are with elayne’s actions but think about a teacher trying to fend of some delusional student with a crush. Unfortunately it happens. But it’s a part of elaynes growth as a woman and dealing with her feelings towards rand. The only “ick” would have been if Jordan would have had thom act on it. Back to the show…Gareth didn’t interact significantly with the ef5 until much later in the series (trying to avoid spoilers). However Bayle was mentioned heavily in TGH. So it explains why he is in this season. With the amount of changes they are making, not just with siuan but with egwene and her story, the ripple effects will most likely lead to Gareth not being around.