1) a 2D drawing should be good enough, but an angled neck pocket might be tricky if you need one.
2) Depends on a few things. If the drawings are perfect, it shouldn't take the programmer long to get it ready to run. Also depends on what size the material is your working with, and how easy/difficult it is to hold down. Whether it's a 1 shot thing depends on how good the guy is.
3) Tearout is always a possibility, especially when using highly figured woods. There are ways to minimize it and try to avoid it. Depends on the guys experience. Bit's should never break or slip if they know what they're doing.
4) I'd say ~$200 for a one off job, maybe more, maybe a little less.
If you can carve the neck by hand, I'd say just do the whole thing by hand. Make a few templates and use a pattern cutting bit.