Quote - ...I would test the process rather early on - maybe even immediately ...

 
Absolutely!! Testing must be an integral part of your pipeline, especially if you plan on distributing as firmware (CD/DVD).  Mistakes discovered after the burn can be costly.

Quote - ...Usually DVD's think of their material as a movie. Therefore the music would be synchronized to the picture. In that scenario everytime the arrow was pushed the music would jump - and that could become annoying to the viewer. However Sometimes the images can be imported into the DVD burning software and literally treated as a slideshow. In that case, the audio might not jump when the arrows are pushed. I don't know...

 
On DVD use "Chapters" to bound your jump points. You can put multiple frames inside the Chapters.  Can be as few as one frame. This allows the background SFX to resync at Chapter boundaries when a jump occurs. As for music,  I suspect in most cases, unless the project is a music video,  it won't be playing continuously throughout an entire chapter.  

Quote - ...*A PowerPoint on a CD may be less expensive that burning it to DVDs (for distribution purposes)...

 
Does a PowerPoint slideshow require the user to have PowerPoint?  Additionally,  there may be other transportability issues.

• Bomac