A few ???

[shortbus]

I'm new to this site but have been reading the posts alot. I'm going to build a cnc plasma table. The dimensions I would like are 4'x4'. My max cutting speed needs to be 300 to 400 IPM and the slowest speed would be 10 IPM. My questions are,,,
With this size table and the speeds I would like, would you recomend using stepper motors or servos?
I would like to use ball lead screws. What pitch should I use for a machine like this and what is a normal diameter for a machine like this?

The lighter the gantry is, the smaller the motor you can use, is this correct?
I have found a local source for stepper motors, servos, power supplies and stuff. I have found that there are several different kinds of steppers bipolar and unipolar. what is the difference? Which motors would be easiest to use?

I can build the whole machine no problem, I own a small machine shop. The wirring, motors, controllers and software will be the confussing parts for me.

Could someone list ALL the major parts of a machine for me using servo motors and using steppers?

Hope this isn't to long, just lots of questions!!