I'm on 56.0 until Ubuntu publishes an update but... if I click on the search glass icon, a dialog pops up with a set of suggested alternatives, and a change search settings button.
No it changed a long time ago. It used to be instead of the magnifying glass icon it had the icon of the current search provider. Then you could click a drop down and change it at any time, and it would stay there until you changed it again.
no, if your default is google, and you search something on amazon, it immediately goes back to google. Which means that you need to do two clicks every search instead of just enter