How does Ekko's Z-Drive actually work?

We've seen Ekko use his Zero Drive, or Z-Drive for short, multiple times in his lore, but it never works the same way.

First we've got his bio:

Instinctively, as if he’d done it a thousand times before, Ekko activated the crystal-containment device. The world shattered around him and he was wrenched backward through swirling particles of time.

In his first use of the Z-Drive he doesn't need to prime it, just activate it and go back a few seconds in time. It doesn't look like he has control over how far he goes back in the past.

The second time we've seen him use it was in his comic.

The moment Ekko turned on his Z-Drive seems to be an anchor point, which he rewinds back to every time. Additionally, Ekko has to pull a chain like a lawnmower before he can rewind. This is the first time we see his injuries persist through rewinds.

Next up, we have his teaser "Seconds".

Again, his injuries persist through rewinds. However, this time the moment he pulls the chain of his Z-Drive seems to mark the anchor point. Apart from that there's nothing unusual.

Another use is in his color story:

Ekko didn’t finish his cake beyond the first bite. Instead he primed his Z-Drive. His home shattered into swirling eddies of colored dust. The thrum of the everyday fell to absolute silence. The moment splintered and encircled him in a vortex of light.

When the fragments of the future reassembled into the past, Ekko’s parents were coming home for the second time that night.

This time his Z-Drive works similarly to it's first use. It doesn't need an anchor point and can just be turned on to rewind. However, this time it rewound multiple minutes, instead of just seconds. Again, it isn't mentioned in the story if Ekko can control how far he rewinds.

The weirdest use of the Z-Drive is in Dr. Mundo's color story:

He repeated himself over and over again (perhaps suffering from a case of physical amnesia?) and had no respect for Dr. Mundo’s authority.

and

But then – somehow – the treatment reversed itself. Whatever good Mundo had accomplished in his last attempt at a cure was suddenly undone. To Mundo’s utter confusion, the child scurried away, utterly uncured.

Usually the Z-Drive rewinds everything but Ekko. In this instance however, it seems like it only rewinds Ekko, making him repeat himself. This suggests that Ekko is unaware of what he said before the rewind. Additionally, Ekko reverses his injuries, aka Mundu's "treatment", which he couldn't do before, further suggesting that Ekko is being rewound. Yet he doesn't continue fighting after rewinding, so it seems like he keeps at least some of his memories, although not enough to prevent him from repeating himself.

I don't get it. Are those multiple iterations of the Z-Drive? Does it have a bunch of different settings? Is the Z-Drive just a magical story telling machine, which works however the author wants it to work?

And one additional one: Why does the Z-Drive affect the Flashbinder? (That thing that was supposed to be a grenade, but starts reversing in time mid-explosion.)