ha! the massive dupes of SOJs will be wiped out, so the trading rate of an SOJ will skyrocket. there WILL be SOJ currency, there just won't be as many.
sure, there's trading now, but it's trading legit stuff for dupes, which will disappear anyway. i don't see the point in trading, unless you really want an SOJ now, and don't care about the future.
the ladder is the same as non-ladder, they have the same items. it's like hardcore, only you get to die multiple times. i think there might be different titles, and of course the whole "i 0wnz0rz j00" bit over the other gamers. so, in short, yes.
that's impossible, unless they have a little thing that slowly takes away the life of anyone in a, say, 10 foot radius around your body. and it auto-deflects arrows. of course, credit for kills this way would be to a quillrat, or a zombie. or daemon. wuteever.
the only way to get rid of most of the things you listed would be to have one moderator in each game, and the moderator would have to somehow be resistant to bribes and the like.