Yes with iPhoto and iMovie you can add as many songs as you want, of course up to the length of your slideshow.
I believe they only have an online version that will work with MAC
iPhoto does indeed allow the addition of music to a slideshow - anything in your iTunes folder.
Have you looked at Keynote? That is Apple's equivalent of PowerPoint.
iMovie works great for what you want. You can batch slides and batch transitions, while retaining the ability to change ones individually. Pull in music you have in iTunes (command 4). There are also some sound effects available. But I think your issue is in burning the DVD. I use other software for that as having found the apple is weak in that area. After exporting the movie, I will burn with Toast Titanium. Very, very easy to do. And, if you ever have a video clip or two, you can add them in as well seamlessly. And, in iMovie, you can do easy titles to boot.
I do use iPhoto and Aperture, but not for slide shows, so no help there.
Good luck
You need to get-or may have Apple tech and warranty coverage. Look in your pamphlet that came with the computer and call. I think it is 289.00 for 3 years and well worth it. They have a iPhoto dept which will answer all your questions. Apple has really fast and great service. Most of what you want is already there in your computer-Imovie etc. People choose Apple for it's great graphics and video. It's simple and very good. Much faster than windows and easier I feel. Anything done in iPhoto must be EXPORTED to somewhere e.g. images or pictures before sending to a Windows via email.
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