1) Goku seems to be slightly ahead of Jackie Chun. When Jackie Chun gets serious, he can speed blitz one shot Krillen.
2) Jackie vs Goku seems to be more about the old master being frustrated with the young kid being able to match his every move. Goku seems to be tougher and more resilient and probably stronger, but ki wise, I don't think there needs to be an advantage. Goku is just the better fighter at equal levels against everyone.
3) Goku wasn't going all out against Metallic.
4) Honestly, there's no way to figure out how ki blasts work, I think I'm going to drop them altogether.