A) Yes
B) Just zoom in to see the segments, they are quite noticeable.
C) Not sure what you mean here. Polylines can contain arc segments, but are you talking about a polyline made up of segments approximating a spline type curve? Being very basic here, there are 2 basic types of curves. Arcs, or portions of circles, and Splines, which are "free flowing". This leads into D
D) Since gcode can not specify spline curves, only arcs (G2, G3) and straight segments (G1), your g-code will pretty much always be the same for a given shape. With a lot of text, short straight segments is the easiest way to do it. That's what you get from every TTF converter I've ever seen. (including CAD programs)
E) Tricky one. I never considered TT fonts as vector fonts, but they are scalable. A little different, though. If they were vector based, then we wouldn't be having this discussion, right?
We have to convert them to vectors to be able to machine them.
F) You can export TT fonts from Coreldraw as a .dxf and import them into AutoCAD, and scale them no problem. They will just be a bunch of polylines, though, so the text would not really be editable in AutoCAD. (such as changing the spelling, etc.) A lot of people use only Coreldraw for all their machining. Just take the Coreldraw .dxf and convert to g-code. No AutoCAD required. Corel may be a little more challenging to get things the correct size, though.
G) I know that here are some sign packages that are quite expensive, and I'm not familiar with any of them. They will give you g-code from fonts with no conversions necessary.
http://www.signlab.ca/ http://www.scanvecamiable.com/products/enroute.asp
Not everyone would agree with me, but imo, there is very little you can't do with AutoCAD. With my macro, you even get gcode. If your doing a lot of text, look at OutlineArt as I mentioned. It will give better results than AutoCAD's Express text explode. You will have to play with the scaling, though. And the width factor in OutlineArt.
I'm working on some V cut fonts for AutoCAD, and I'll be writing a macro to make it easy to use them. It'll be a while though, as it's quite tedious and I don't have nearly as much free time as I'd like.