Good morning,
Thank you for your query
Point 1, when did you start experiencing the issue, as we are aware of an issue with this and a fix was put in place yesterday. Could you please re-test this functionality and update us?
Point 2, there is currently no way of reverting back to a saved masterpage, to correct this you can either edit you existing masterpage to what the information was before or you will need to create a new masterpage.
Point 3, there is an option to select the question type as Multiple Choice. You will need to create your question first with the question type set to Multiple Choice, then from the Definition page Right click on your multiple Choice question and select "New Response", this will then insert an new response by double clicking on this it will open the Edit Response Caption: for you to rename the response.
Kind Regards
Cara Gibson