It means that Hack's complete fodder compared to the real big-shots or those who are part of the royal family.
Not really.
Dellinger was not able to go through Bartos barrier. Even Diamante presumably in short exchange started to attack Rebbeca verbally as Bartos barrier seemed to stop him from attacking her physically.
If by royal family you mean Mingos crewmates.
Bellamy took out - most probably in same way as Hack was taken out so by big part thanks to fact that Barrier that Barto produced at last moment is suprise for his enemies - Vice Admiral Maynard. Rookie VA or not- still he was Vice Admiral.
So its hard to say how strong is Hack. I would say that he can be as strong as pre time skip Supernova like Drake for example(commodore/rear admiral Drake) or even stronger.