When he gets to his hiding spot, Lennie is most concerned that George will "give him hell" and that George won't want him anymore. He's oblivious to the murder he's committed and its repercussions. The only thing that's real in his world is George's companionship--even when George "gives him hell"--and the rabbit farm they plan to have together someday.
The second part of the question is a bit ambiguous, but I'll take a stab at it. We are brought full circle to the novel's opening scene here, when George and Lennie had been driven out of town because Lennie "just wanted to touch" a woman's soft dress and the townsfolk that assumed he had more nefarious intentions. They had escaped and we find them here, at this hiding spot. Then, George had also been angry with Lennie for carrying a dead mouse in his pocket (to pet). Somehow, George's anger is soothing to Lennie, probably because it's part of their relationship that he can and does remember and count on.