The answer to all your questions is simple. Everyone uses Cam for everything from single part protypes to high volume production. There is no reason to stop your machine from running just to program a part.
There is no advantage to hand written code. If it runs the machine and makes the part, it's good code. No one cares if it's done in 10 lines (optomized) or in 10,000 lines.
The Cam system (Edgecam at least) will give you all the additional things you dont get from doing it manually. Tool List, Setup Instructions, Pictures of the part layout, Machine simulation, A record of past jobs, The ability to update a complete program from the updated Cad file. To name a few.... All of these are a by-product of the programming process.
Mike Mattera
Tips For Manufacturing Training CD's, DVD's for Mastercam, SolidWorks, Inventor, G-Code Training & More
http://www.tipsforcadcam.com