When Hiro protests that Daphne shouldn't be able to move, because he stopped time, she replies, "Well, you don't stop it completely, or we aren't having this conversation." Gives a glimpse into the writers' intentions anyway.
It gives a glimpse into their ability to rewrite the story logic on the fly as it suits their purposes at any given moment, that's for sure.
But it doesn't matter if Hiro only slows down time; Daphne wasn't using her powers when Hiro did his little killing-Ando magic trick so she wouldn't have a clue if he suddenly slowed down time. She couldn't perceive it unless she were using her own power at the time and Hiro didn't give her any advance warning.
The writers could use time travel as the excuse for the magic trick, but the main reason they wouldn't is because it would be hard to have Hiro explain for the benefit of the audience in a clear and concise fashion compared with stopping time.
Perhaps they realized the difficulties mentioned above with stopping time completely, and chose this way to deal with it.
You are being
extremely generous.

They don't give a damn about whether anything they write is possible. They just alter things this way and that depending on the needs of the story at any given time. Just look at how they've dragged Sylar all over tarnation...
And speaking of Sylar, I just remembered a little wtf moment, when he saved Claire from the vortex and said he could "feel her pain" when he touched her hand - referring to his removal of her scalp. Since when is Sylar an empath? Since when is Claire? Where did he get this from?
Or is his seeing power now interacting with the healing power and resulting in a whole new type of power? That's not a bad idea, except that I suspect it's yet another retcon for poor Sylar. He's being tamed down because now he's [Clinton drawl]feeling yore pain[/Clinton drawl]. Ah, something else for the Sylar-fundamentalists to howl about.

He's gonna be Phil Donahue by the time they're through with him.
I thin your explanations of how Ando is not killed are to complicated for the writers of this show.
I think Hiro simply improvised without thinking it through (again).
He really stabs Ando, but in a non-vital spot with the intention to teleport him to a hospital as soon as the others leave the room.
That's still a pretty psychotic thing to do. Hiro is supposed to be sweet and cute. I don't buy him as the type who'd stab Ando for any reason, even if he thought he wouldn't die. (I also still don't buy Hiro being capable of burying Adam alive.)
And the writers have no issues with complicated scenarios. People are bailing on this show left and right due to it all being too complicated to keep straight.
It's fine that Hiro's powers don't take into account actual physics. I'm willing to suspend that belief.
But, the writers should have a consistent explanation and definition to Hiro's powers. They should understand how in the universe of show the powers work and they should STICK to it.
It seems everyone's powers adjust to what the plot requires and that's just bad writing.
Yeah that's the real issue here. We were lead to believe Hiro's powers do one thing and now they do something else, which would be okay except that 1) it's less cool the new way and 2) it's obviously just for the convenience of the plot, not because it's a good idea in and of itself.
If Mohinder would have killed Maya in a messy fashion, however, I would have given it an Excellent.
I think that's coming. Maya has no reason for existing other than to be some kind of breaking point for Spider-Mo. He kills her, snaps out of it, and descends into a guilt-ridden moral wallow, which takes him...somewhere. I dunno what the point of his story is.