well the standard ar-15 is a colt. but now these days the most poopular are generally either DPMS or Bushmaster. the best of the Best is Barret and LWRC.
Not enough information to answer the question. You should contact DPMS customer service.
DPMS doesn't make an AR-15 - AR-15 is a copyright of Colt Firearms, and thus, only they and companies licensed by them to manufacture the rifle can actually call it an AR-15. As for their AR-pattern rifles, they typically come with a 5.56x45mm chamber, which is also capable of handling the .223 Remington.
It uses the direct impingement system.
Depending on accessories, barrel, and condition; you shouldn't pay more than $1,400. Unless it is piston operated.
How much do you want to spend? DPMS, CMMG, Double Star, Colt, Les Bauer, POF, Bushmaster, LMT, Noveske... all make AR-15s in different price ranges. All do what they're supposed to.
Either you have a DPMS rifle, or a PWS rifle. DPMS makes several different models of AR-15, and value can range from $600 to $1500, depending on the exact model and features. PWS, on the other hand, is a different matter. PSW manufactures higher end gas piston and direct impingement uppers, which typically sell new for $1500 - $2000. Overall value of the rifle would depend on what lower and accessories you have.
400-3000 or so depending on specifics
$1200 in 2012 You can get a lower receiver for an AR-15 for about $100 which must be purchased through an FFL dealer. You can the rest for about $500 as a kit.
$600 - over $2000, depending on specifics.
Nobody. M16 is a military nomenclature specific to variants of the AR-15 rifle in 5.56x45. The rifle which the M16 was derived from - the Armalite AR-10 - was in 7.62x51 and does not have an "M" series nomenclature from the US military, as it was never adopted into service by the US military. As for civilian variants of the AR platform, there are many manufacturers - Knight's Armament, DPMS, Rock River, Bushmaster, just to name a few.
$1200Kplus tax. The ammo is going to cost $400/1000 rounds. in 2012