Hi, yes you can add sound to a hotspot, but the problem is (as you observed) that it will play as long as the sound last. It will not stop changing the scene. What you can do is add sound to a scene without a hotspot. Once the scene starts, so will the sound. I know It is not the same as what you asked for. I imagine that you want the user to choose if he wants to hear a description or not and if yes that he chooses when.
Regarding the other issue you asked for, you can add a hotspot and under actions of it choose map and there "link to map". Then it will "display another map in Map Viewer" as the Action description says. That for, first you have to create in PS or similar an image with the text you want to display and respecting the size of the mapviewer and load that image as a map.
Good luck, Martin