I assume that it looks/works in similar way on most Nexus devices.
Simply a short broadcast message, that can be very annoying if your network uses it.
As with Android 4.2 and above Developer Options are simply hidden under Settings.
As on recent HTC phones.
When you’re on start of the app launcher, pull down with your finger once to reveal a menu type thing where you can select how to view and such. And to the right you have Menu where you’ll find Grid Size, simply select 4 x 5 to display a total number of 16 apps (it uses one row for other things).
Google Now require at least android 4.1 so not all phones will have it right now, but most unbranded One X/S and all One X+ got it.
More on what Google Now is can be found here