Three questions about Hulk in this movie (Spoilers)

(1) Regarding Hulk's powers, shouldn't Hulk be killing Hela's gigantic guard wolf in two seconds? I was surprised that wolf was giving Hulk a difficult time. Isn't Hulk's skin nearly impenetrable and hard as steel, and able to block direct tank rounds? How is a dog tooth getting through his thigh?

(2) Although it might have been explained in the movie and I missed it, but how was Banner stuck in Hulk Mode for two straight years? I thought Hulk only stayed that way when he was angry and surrounded by threats. But in his apartment, Hulk looked kind of content in that nice place and was not under any serious threats and stress. How is he still green Hulk?

(3) Is Hulk evolving? Because he seems more lucid and in control as the green guy in this film. He's having basic conversations with Thor and Valkyrie. It's still caveman talk, but his sentences and control of his emotions seems miles better than previous MCU movies where he would listen to no one, except for Black Widow (and even then, it took a lot of work).