If you want 12 CON then you can only have a max of 14 STR. 15 WIS, 14 STR, 13 CHAR, 12 INT, 12 CON, 11 DEX is the closest you get to your desired ability points or 16 WIS 15 STR 13 CHAR 11 INT 11 CON 9 DEX
There are no rolls, you just toggle between fixed sets. http://nw-forum.perfectworld.com/showthread.php?78361-Ability-Scores-List-of-all-possible-rolled-combinations is a list of all possibilities.
In case of the DC the "human > all other races" are even worse, because there is no race where you can get +2 wisdom and +2 to a DC secondary stat. So the disadvantage of humans only getting +2 to one stat doesn't matter at all, when choosing a race for a DC. On a side note, what are the stat bonuses for drow?
Well, a half orc would do more damage, while a human would have better defense. The Build suggested by the TE does use the 3 "human feat points" in a defensive talent and humans also get +3% defense.