A1-It's pretty much what I did except I haven't purchased NC3 yet, but will soon.
A2-Tone curves are more or less the same thing as the output curves you adjust when color-correcting images in Photoshop. If you've adjusted curves in Photoshop then you know what I mean. It's easier to do than explain.
A3-NC3 does not, I believe, have standard tone curves. It's easier than that. You take a typical shot with your camera. You color adjust it in NC3 to get it to look right. Then you upload that adjustment curve to your camera. Now when you use this custom tone-curve in your D100 you get all this processing in-camera. Verrry nice. This is the ONLY reason I want to buy NC3. This way I can tweak my JPEG output to look just the way I want it when I expose it the way I normally do.
A4-Yes. Someone on this site had a copy. Search the threads and you should find it.
A5-Photoshop does far more than Bibble or NC3. I think you will want some sort of powerful image editing software. Some options are Photoshop Elements or PaintShop Pro, but quite frankly Photoshop is the thing. See if you can get the Academic discount which is about 1/3 the cost of retail. Photoshop it worth having if you can afford it.
A6-Plenty. I'm doing my image editing on a Dell refurb 1.7 Ghz with 512 Mbyte and it flies. Shoot, I can even do a decent job on my 600 MHz laptop with 384 Mbyte of memory, and it's not at all painful. (The screen is a different issue, but it's usable.)
I've had my D100 since the first of July, and I went through all the problems others reported with this camera. The bottom line is that it is not a point-and-shoot SLR. You actually have to learn to use it. What throws most folks, including me, who are familar with film SLR exposure is that the way the D100 matrix meters is slightly different than the way film SLRs meter. The digital cameras hold back highlights more, resulting in what film shooters might regard as underexposure. Once you know this, you can adjust, just like for any camera. If you go back to the basics, and zone meter (use the spot meter, then set expsoure to render that spot the desired tonality) you will discover it behaves just like any other camera, and it's dead-on. While film SLRs are often matrix-meter-and-shoot-it, digital SLRs require more thought about exposure compensation even in matrix mode. It's not film, so it takes a while to learn its quirks, but it's a fine camera. As usual, the weakest link is the nut behind the wheel...