For the navigator, does it work if you push the enter key after you use the arrow keys?
Also with the navigator you can highlight the zoom value use the arrow keys and before you press enter hold the shift key so the values stay highlighted.
Then you can enter another value without having to highlight the zoom percent.
The second one it looks like your seeing the pixel grid: View>Show>Pixel Grid
Or it might be the regular grid: View>Show>Grid
Yes, hitting the enter key works, but wish it were interactive like the other controls - Layer Opacity for example - pixel peeping and having to keep hitting enter is not as productive as just holding an arrow key down.
You are right about pixel grid being set as on - never used that before so must be on by default. Now I know that pixel grid activates at a zoom level of 500% - lower magnifications and you don't see the grid.
Thanks - leaned something tonight
Now off to bed
Instead of the navigator have you tried the scrubby zoom that is in Move Tool options on the tool options bar?
Or the Animated Zoom under Edit>Preferences>General?
I have tried the scubby zoom, but with Wacom Pen in one hand and finger on the up/down arrow would be much more efficient in speed retouching, especially when working on large batches of files.