As for the first issue you've addressed: if he's spamming in-game, simply /mute [his_username]. You'll need OP to do this though, obviously.
If he's spamming your inbox on the forums, you can hit the Report button on the top-right corner of the PM, and it should be dealt with.

As for the second suggestion: I agree with having a full set of commands added to the /help command as it is horribly outdated. For now, take a look at this thread, it should have all the operator commands on the second half of it.