About the deadlift, a 400 lbs deadlift is nothing to write home about, especially for someone my size. Nevertheless, it does make you a lot stronger, it just requires caution. If you're young you probably shouldn't be doing it.
From what I've read, most normal men could deadlift 400 lbs with adequate training. Certainly the laborers of the past became accustomed to lifting loads like that.
Nevertheless, it is a sort of milestone, sort of like lifting 225 on bench press.