sound stage, imaging in 2 seater

2)  Speakers are more like light bulbs than lasers.  They don't project their sound directly forward.  In fact they only start to beam at upper frequencies, that frequency being determined by the cone size of the driver.  Try reading my "Advanced front Speakers" thread above for more information, mainly what I write on page 2. 

3)  That depends on your definition of "quality".  I've found that peoples definition of this is greatly effected by their experiences.  If you have experienced a really good sounding system, then that is your reference point to use on your own system.  Working on your experiences and knowledge will greatly help you in building your own system.  This is a very time consuming, but will be worth it in the end.

Speakers only in the front is prefered by many people, like me.  The front sound stage is all that really matters.

I think this relates to the orginial topic...  Why is the front sound stage the only "important" part?  I couldn't figure out how to explain that to someone.

The very basic reason is sound is supposed to come from in front of you.  Your ears face forward.  When you listen to a live performance (concert) you generally face the stage for the best sound.  The ideal way to listen to recorded sound is to face the source.  So in a car, you want the sound to appear as if it's coming from in front of you.  Since that's where the windshield lives, you have to compromise of course.    You do not want the sound to come from behind your head as this is not natural.