mtg double strike rules?

[Juice]

OK I have a couple of questions about double strike that I can't find clear answers for. Do creatures with double strike deal combat damage twice each time they attack? I understand it deals first strike damage and regular damage but does this count for combat damage once or twice?
Lets say I have a Kor duelist equipped with a banshees blade and I attack unblocked.what would happen, would he deal one first strike damage then two regular damage before becoming a 3/3 or would he just deal one first strike and one regular damage and become a 2/2? Can anybody explain this to me? Thank you for your time.

[Brock]

So it starts as a 1/1, during first strike damage it will deal 1 point of damage then banshee blade will trigger placing a charge counter on it making Kor duelist a 2/2. Kor duelist then deals regular combat damage as a 2/2 dealing 2 damage. banshee blade once again triggers making Kor duelist a 3/3. So by the end of it's first full turn of combat kor duelist has become a 3/3, dealt 3 damage and banshee blade has 2 charge counters