Can an .mp3 track be added to a presentation (as background music)?
No, the software doesn't support adding an MP3 file to a presentation. I've installed the product and checked every menu and option in Insert, and there is nothing available.
For example, Microsoft PowerPoint supports adding an audio file to a presentation: https://support.office.com/en-us/article/Add-and-play-sounds-in-a-presentation-c547669a-8845-45ae-a573-8515017e93d5#bm2
