No, thank you! I also worked on Kindred and on [SOON FOR REALS]. Indeed, in story, Ekko can use his abilities. There were a few sketches I wrote that broached how this would look/feel to people around him. Onlookers would most likely see a bruised kid suddenly take down an opponent by exploiting every weakness.
A big key thing to understand about Ekko is that his Z-Drive doesn't always work the way he wants it to, mostly owing to the fact that it's homemade hex-tech that runs on the exotic properties of a shattered crystal.
In terms of Parallel Convergence, (story wise) is what happens when you wrinkle time too much -- sometimes it tears and your parallel self lends a hand to seal the breach. I mean, he's the boy who shattered time. That can have some unintended consequences.
With Phase Dive, Ekko basically blinks out of the timeline, returning at opportune moments.
As you can tell, he's probably made (and broken) a few Z-Drives.
The Timewinder feeds off his Z-Drive. However, he initially designed it to have an entirely different function -- probably a smoke or flash bomb -- but... it didn't quite work as intended. In fact, Ekko's sort of unsure about how it works, but it works reliably enough (and with no lingering effects) for him to be cool with chucking it around all willy-nilly.
Thanks for making me think about this stuff. One of my 2016 goals is to write Ekko a long bio, and you're inspiring me to put it before my other work that has deadlines (because I am a triple-A rated procrastinator -- heck I'm supposed to be making my wife bolognese for dinner at the moment).