Look at UI Bubble Popup example scene.
This scene shows how to make such a tooltip.

Allow Camera Control enables / disables camera control at all.
If you want to prevent rotation on one of the axes, use Camera Rotation Speed. In your case - (0, 1).

I'm having a bit of trouble to figure out how I can create and use more complex tooltips for markers.
My tooltips should be a texture box with a button in it and a bit of text and logic (the button should only be enabled when the GPS location of the user is inside of a specific radius of that marker). Also this tooltips should be opened as soon as I click on the marker and should stay open until I tap on another marker or the map.

How would you do that?

Another question is if I can disallow the tilting of the map? When I uncheck the "Allow Camera Control" function, I also can't rotate the map anymore. I just don't want users to be able to tilt the map into 3D mode as this looks kind of strange.

Thank you,
Cheers, Robert