The latest versions of Macs can use either DVD-R or DVD+R. For the longest time it was only the former, but Apple gave in to the format battle.
Dual layer discs have two layers of data on one or both sides of the disc. Hypothetcially, you can have four layers of data. Most video DVDs that you rent have two layers and when there is a slight stall in the video about halfway in the movie, the player is changing layers (going from the first layer near the inner ring of the disc out to the outer ring of the second layer). If you have a dual-layer dual-sided disc, you will have to flip the DVD. Any DVDs you buy or rent with no label usually have one verion of the movie in widescreen and another in fullscreen.
As for the DVD+/-R debate, it's all dependent on what works with any DVD player you might put it in. Most of them list their compatibility. Dual-layer recorders are available, but not standard in Macs (yet) so you will be burning single-layer only.
I'd check out the iLife applications and start messing around with it. Spend a little time and money on blank discs and see what you can come up with.
Hope this helps.
cpjakes
