I can do my best at least - but neonknight has explained the basics. I've been playing since it came out 2 years ago, and where in my younger years that would have ment 2-7 times a week for 2 years, now it more like 1-2 times a month for 2 years.
The quick start rules are here: http://www.wizards.com/dnd/TryDnD.aspx
Basicly you don't need huge spaces to fight in, but the more challenging the map is, the more fun it is. Example - last game, one of my monsters used his sliding power (slide enemy 3 when hit) to push a character down a pit - which happened to contain a gelatinous cube - great fun for all... or was that terror...?
But even though places to slide people are fun, having tight quarters with corridors crossing running from room to room is also fun.
And - just at note to GP - for a fighter to "mark" an enemy he has to attack him so sword vs. bow doesn't work here