LLC is Load Line Calibration, and it basically tries to prevent voltage from dropping when a load is presented. Vdroop is actually a design feature from preventing to much current rushing through the cpu, but if it drops too low will cause your computer to crash. So many mobo's now allow you to set how aggresively you want to prevent the vdroop. I'm not at home right now, but I used the 1 step up from normal.
An offset is used so that it'll add that amount of voltage to the base amount (Base amount varies with O/C), and is useful so that instead of always being (pulling numbers out of thin air) at 1.35v, it would be at 1.1v and add the offset of .25v when a load was presented.
I used the software to manually find a stable O/C because it was a bit faster, plus if it crashed I didn't have to worry about reseting the bios.
After you find the voltage, multiplier and temperature that you're comfortable. And doing a something like Prime95 for a few hours to see if its stable, you can use the Offset to get the voltage that you had used in the Asus software.
I put in the offset and use Prime95 to see if it equaled the voltage I was aiming for, because as I said before the base will actually be different for each clock.
So for my example the computer I built was normally at 1.6-1.9 ghz when I was web browsing and 4.6 ghz when I was gaming. Saving me power when I wasn't putting a heavy load on it