The score out of 800 and the score from the essays (AWA) are two totally different scores. You are correct that you will get your "unofficial score" out of 800. So for example you will leave the testing center knowing that you recieved a 550, 650, 710, or whatever you get. But the AWA score will come at a later date (about 2 weeks). The AWA score is based out of 6.0 points and goes in half point increments. For example you could score a 4.5, 5.0, or 5.5 etc... It is generally considered acceptable if you score a 4.0 on AWA or above.
This AWA score will not factor into your 800 score in any way.
If you have any further questions, let us know!
Best of luck on test day
(Read here for further information on how scoring works: http://www.mba.com/the-gmat/gmat-scores ... eport.aspx
New to the GMAT Club? <START HERE>GMAT Club Premium Membership - big benefits and savings
My GMAT and BSchool Tips: