[JimmyK]

Wow, your realling looking at the complexities of local controlling here. Its a little over my head for where I am at in my training right now, but, from just glancing over the questions it sounds like a lot of the questions you ask fall under the best judgement rule.

This is the foreward to the 7110.65

"This order prescribes air traffic control procedures and phraseology for use by personnel providing air traffic control services. Controllers are required to be familiar with the provisions of this order that pertain to their operational responsibilities and to exercise their best judgment if they encounter situations not covered by it. "

A good controller isnt going to get themsleves into some of the situations you described because well, thats our job, to see those things before they happen. A good controller isnt going to have to make the decision who to send around or who get there take off clearannce cancelled becasue he/she will have seen the conflict setting up and then take the propper actions necessary to avod it. But then again controllers(and pilots) are human too and not perfect, people make mistakes and sometime situations like you described happen and thats where the best judgement rule comes in. $h1ite happens and something has to be done so we have to use that good 'ol human ability to reason to figure out the best/saffest way to solve a problem.