[thufir]

1. sure. You can judge OP several ways but monks have very good damage avoidance and very good DPS, coupled with FD.
2. yes, although their aggro control is kind of dubious. obviously they are good at losing aggro but they can only get aggro through DPS and procs - kinda like a warrior without the taunt. The upside is that they do more damage than warriors. A monk tank can generally get aggro at some point during the fight, but the monk's lack of snap aggro might make for some irritation in the early stages against a tough mob if someone lands a debuff early and the mob goes straight for them.
3. this depends on group composition and where you're fighting. knights have aforementioned snap aggro which can be a real help in a group with an enchanter or other squishies. equipped properly monks can tank about as well as a warrior can and do more damage while doing so, although they have fewer hp so clerics might complain about the CH. generally a monk tank will do ya just fine, although having to both pull and tank is a vague hassle if nobody can hold aggro on the mob while you go get another.