I belive the AIM issue has been addressed (it BTW is not unwarrented surveillance, you used company assets to send the AIM messages, they are entitled to monitor their own assets). Let me address paragragh 3 somewhat.
Can a company fire you for information they found from sources outside the workplace. Certainly they can and often do. People are fired for a multitude of things not found offically through the workplace such as:
Publicly embarassing customers or company - there was a recent case of a waitress who got fired for posting on the Internet a note from a pastor commenting on tipping. Others have been fired for blog entries or Facebook posts. Assume no privacy for anything you write or post on the Internet. If you would not want your manager to see it, don't post it. This goes for other types of writing as well. It's less common to get fired for a book you wrote, but it could happen.
People have been fired for getting arrested, for hitting on the CEOs wife in a non-work setting, etc. People have been fired for their politcal beliefs or their religious beliefs. In an at will state, they don't have to say why you were fired, so these thigns are becoming more common. I read storeis inteh last election of people being fired for having a bumpersticker on their car for a political party that managment did nto support. Some of this can be fought in court, but it is often costly and very time-consuming, so usually the companies get away with this stuff. The smart ones never give this as the official reason.
Getting fired for someone finding out from outside sources that you are looking for a new job is not terribly common. However there are times when it might be riskier such as:
- when the boss is a control freak
- when a large bonus is due to be paid soon
- when a perfect replacement for you just happens into their lap (if it
won't cost much effort to replace you, you become much more
- when they are getting ready to start a new major project with you in
a key role
- when they are already thinking of replacing you
- when there is a layoff coming up
On the other hand, you can't avoid looking for a new job because someone might find out about it. If you want to leave, then look for a new job. JUst be a bit close-mouthed about who you tell and don't let the new company check with the current company in a reference check. And don't use comapny assets to look for new jobs again.