To answer your questions ..

1. No one knows when the skillbreak of Yamato will be released .. Only the team that works behind the scenes knows the answer about that ..

2. It is good to take reference from other game versions but it is useless too sometimes, CN released Yamato's skillbreaks but who knows if the EN server will ever get that skillbreak .. It maybe not, or maybe the next 3 years .. Only "them" knows the answer ..

3. I have no idea how Skillbroken Yamato works ..