Painting, Airbrush Questions

Hello Everyone:
  I am thinking about getting an airbrush to do some painting of my
minatures 
and I have a couple questions.
  
  1) What type of paint should one use with the airbrush?
	A laquer type paint, acrylic, water bases, oil based what?
  2) How many coats of the paint does one normaly have to use to
ccompletely 
cover a minature?
  3) How narrow (wide) of a area can one paint with one pass?
  4) The paints at the hobby store for models are expensive.  Can I use 
something from Home Depot or a hardware store? (related to Q#1)
  5) Is it worth getting an airbrush?
  
  If some people could help me with these questions (or any I have not
thought 
of) I would appreciate it.
  
  Thanks
  John W. Fox