No, because they're under 21 so dont need to be registered. I believe they will be home grown from next season as they have been with the club for 3 seasons before their 21st birthday
b) There are several contenders for Owen's place. Welbeck, Bebe, Cleverley and Obertan will all be 21. Some may go on loan (Bebe and maybe Obertan would accept that). I doubt that the others will accept to be loaned for 2 years in a row.