Alright, time to answer some questions.
Why did Yamamoto call Adam a traitor?
Mayuri is hiding things from him, like always. He didn't tell him who Adam was because Mayuri wanted to use Adam as a Guinea Pig.
Why didn't Adam use his Bankai?
Because it would've affected the entire seireitei, possibly killing Ichigo and the others. Beyond that, had he used it, Yamamoto would've used his, and when two Bankais of that level meet, the most experienced one wins.
Will Adam be rescued by Ichigo?
Hell no, he escapes the Muken. He isn't just a Shinigami, he's one of the Wizard Saints, that should give you an answer as to how he escapes.
How strong is Adam?
Right now, high captain tier. Stronger than Byakuya, the ice kid, nerfed Kenpachi, and the others but around the strength of Shunsui and Jushiro.
Will this novel cover all the arcs?
No, Adam's presence will expedite many things, including the confrontation with Aizen. To spoil things, Adam will return to Fiore soon enough.
He will return to Bleach eventually because of Yhwach but after Aizen, home.
The final antagonist of the novel will be Yhwach?
No, it will be someone far beyond anything Adam, Ichigo, and even Yhwach have faced.
Any other questions, leave them on the comments.