OK, here goes...
Yes, the mic pre's on the D1600 are OK, and before I got my Audio Buddy, those are what I used. But, when I got the Audio Buddy, mic levels became so much easier. You do have phantom power on the D1600, but I have found that the pre's just aren't easy to work with. You have to use the top decibals of the gain to get any signal on good condensers, and even then they are severely touchy. It is so much easier to amplify the signal and not have to worry about distotion or topping off the gain knob.
C1- I hear it is great for males, but not so great with females. I am sure Alan Hyatt could shed a little more light on this, or maybe someone who uses the C1 a lot.
My personal bias for going for the 4033 first for me is that I play drums, guitar (ac and elec), bass, piano and other random things, and the 4033 is proven to do well as an all around mic. Not taking away from the C1 (I want one almost as much as I want a Taylor acoustic) it just doesn't make sense right now for me to add that to my mic cabinet.
As far as compressors and monitors- RNC from FMR audio gets rave reviews from everyone who has used it. I have NEVER seen a bad comment about it. I use
a DBX 266xl and I am very pleased with it, but If I would have known about the RNC when I bought my DBX, I would have spent $20 more for it.
I am in the major minority around here in not caring for the Mackie monitors. I am sure someone will come along shortly and let me know why they are so great, but I just don't prefer them. This is why monitors are so subjective... you must listen first.
As far as the 24/4 16/8 question, I could hear the difference. I haven't heard the difference in the two when burned to CD, but at least through the D1600, there is an apparent bump in clarity as well as an overall unobstructed tone from 24/4. I use a lot of tracks, and 16/8 is what I usually use, and I think it is fantastic, but the 24/4 does give a little more of a "pristine" quality to it. BTW, I usually use
www.korgboards.com for good D1600 advice, if you haven't already. They don't seem to want to add a korg forum here, and a lot of people from this site show up over there as well. It is a great resource.
Pete