A timestamp feature is not available but you can try instead the notes element. You can check our documentation regarding notes or any other tips here:
http://interactbuilder.screenstepslive.com/s/5404/m/16264/l/167241-notes

Let us know if you are still having this problem after yesterday update.

Hello Trevor here is a sample app for this situation:
373 - Drag behind element.zip

In order to move an element behind another and to be able to drag it again after that, you will need a transparent element on top of every element. This transparent element will actually drag itself and the element that should go behind the other element. Thank you for your feedback.

Do you have Execute on Page Load set to Yes in the Behavior Options window for the Show behaviors of those 2 texts?

This option is not available, but it could be a nice feature in the future. Thank you for your feedback.

You can do this using Intersections. This are the steps:
1) For the Hanging hat add a Drag-Move behavior.
2) On top of the character's head add a transparent element.
3) Add the other hat in the right position and make it not visible on execute.
4) Now add the following intersections between the hanging hat and the transparent element: one intersection with Hide behavior for the hanging hat;