At the beginning of marineford, both the admirals and Mihawk were using their most powerful attacks that we have seen on screen.
Kizaru: Yata no Kagami
Aokiji: Ice Age
Akainu: Daifunka
Mihawk: Gigantic slash
From the reader's perspective, these are the strongest attacks they respectively used. See, Mihawk wanted to test his power against the strongest man in the world, it doesn't make any sense that he used a low or medium attack from his arsenal, the same thing goes for Kizaru, it doesn't make any sense for him to start the attack against Whitebeard using minor attacks from his arsenal.
At worst, these are high-level attacks from your arsenals of power. The only chance we see anything stronger than that is if the admirals show the DF-awakening and Mihawk shows some new trick, other than that, we can clearly see that they can even be his finishing attacks.
So yes, Marco and Jozu blocked very powerful attacks, and both could certainly replicate that Zoro feat in those same determinations (stopping the attack for a split second, needing the help of Law's teleport and getting extremely injured after that)
Do you think it takes a few seconds for high-level characters to move a few meters? Obviously not
It is impossible to measure time using panels in the manga, in reality, it must have happened in less than 1 second. It is impossible for supernovae to take a few seconds to leave a certain area, the subsequent dialogues are inconsistent. I can give you a taste: Whitebeard talking while Kizaru's lazers (speed of light) travel: