Interesting I see this topic as my computer works on churning out fourteen copies of a DVD I authored.
Hardware:
I'd recommend getting a Dual-Layer drive, since it will still burn single layer disks, and can do dual layer when the media gets to a suitable price. Almost all current drives can burn both -R and +R disks, which is almost a requirement nowadays.
Remember your burning speed is going to be limited by both your drive and your media. On one of my burners, I burn at 4X because of the drive's limits, and on my other at 8X because my media is the limit (the drive can do 16X). I'd say get the fastest drive you can, and let the media be the limit, so as the faster media gets cheaper, you can burn faster since your drive will already support it.
If you're going to need to burn a lot of disks in a short time, I'd recommend getting more than one and a recent copy of Nero, since it can burn on more than one recorder simultaneously. I've got a Pioneer A06 (4X) and a Lite-On SOHW-1633 (16X, DL 2.4X). I paid $160 for the Pioneer in 2003 and $70 for the Lite-On in 2005, both when they were fairly new. You should be able to get an excellent drive for under $75, including shipping.
Software:
I've used a number of authoring programs, and I'm partial to Sony's DVD Architect ($675, as part of the Vegas+DVD suite, not sure if you can get it seperately anymore). I had a number of problems with Adobe Encore 1.0 ($350 for latest version), including the dreaded "Unknown Error: -1" that I never managed to rectify. Reportedly, later versions (currently at 1.5) are better, but I've never gone back to check.
Ulead's DVD MovieFactory ($80, often bundled with drives) is very simplistic, and not really useful for any kind of advanced authoring. I've never tried DVD Workshop ($395), so I can't speak to how good it is.
Also a possibility is
DVDLab Pro ($200), which is my second choice to DVD Architect.