Put your pre at the same place it would normally be. The gain on the comp. is to get the level back to normal after the level of gain has been reduced so drastically.
MS stands for miliseconds. And s stands for, you guessed it, seconds. The number is how long it takes for release=how long it waits to take the gain reduction off, and attack=how long it takes to apply the gain reduction. Just play around with it, and you'll get the hang of it.