I don’t know what Walker will do but I can tell you that he will endorse whomever the GOP tells him to endorse. I think if Rubio was still in the race it would have been his choice.
He is also very close with Paul Ryan and Priebus. Walker is a fiscal type of Conservative not so much on the social issues though. He does need to make a choice before the April primary if he is going to endorse anyone. I highly doubt it will be Trump but he won’t go against the party’s wishes either.
As for how WI will go I have no idea.