Putting multiple slideshows together in iDVD

[mental69]

I have a project to do for a school graduation where I have created 12 slideshows, each with seperate audio soundtracks in iPhoto 08. I exported these slideshows as 12 MOV files - in 4:3 for iDVD - and they run 200 to 700mb each.

I need to combine them into a single slideshow to play on a DVD - but when I drag them into iDVD 08, they burn and are seperate chapters that I can't seem to arrange properly, or get to play sequentially as a single slide show.

I tried to export them into iMovie, but conversion into DV stream using QT causes the images to look terrible, and using conversion like h.264 makes them too big.

In short, when I strung them together in iMovie, with transitions, and a credits page, the result is 10gigs, even when I compress on export.

Any recommendations?
Can I bring the slideshows straigt into iDVD and do transitions there? can I string them together?

What is the best compression to use and still have good enough image quality on a DVD?

Help and thanks!
Mental - Denver