A- I think Jose brought Sanchez in because he felt Martial was not yet ready to make that LW position his own, not because he doubted the lad's talent. Martial is one for the future, it's a safe bet that Jose would feel the same way given his experience within the game. I do think Jose had an issue with his attitude though, but in a recent interview Martial indicated he was prepared to knuckle down and work towards a common goal (he also indicated, in no uncertain terms, that Jose would absolutely not be receiving a Christmas card this year. But that's another story). The contract was offered shortly after said intervew.
B- True, but Jose has criticised everyone at the club (including non-playing staff) during the 3 years he has been at the club. I would hope by now the players have learned to take his (largely unwarranted) criticism with a grain a salt.
If Jose didn't wish for the club to extend Martial's contract, would he not have transferred that information to Woody beforehand? I mean, you would expect the club chairman to seek the manager's approval before he offers one of his players a new contract.