As of now, it is not possible to take back trust points. However, this may change in the future.
Although Trust Points are intended to be for outstanding answers, you can award a contributor a Trust Point for asking a good question, or any other community activity.
At this point, trust points cannot, and will not, be removed by anybody for any reason.
It is not really possible.
No - it's not possible to deduct trust points. Once a trust-point is awarded, it's there permanently.
No, it does not.
If you give a sensible, informative answer, people can award a 'trust point' - The person awarding the point has the option of leaving feedback - where they can comment as to why they feel you deserve the point. However, some people see them as status symbols and 'beg' people to give a trust point for their answer. Once a trust point is given, it cannot be taken back.
When you register on WikiAnswers you submit your email. When you receive a trust point, you also receive an email stating that you have received a trust point. The username or IP address who gave you the trust point will not be included however. You can also look on your profile page and see the trust point count.
Trust points are usually awarded because people find an answer informative, helpful, detailed, stimulating or even amusing. They are NOT however an indication of the expertise of a contributor - since people can award a trust point for no reason at all.
You do not specifically receive an alert when someone gives you a trust point. However, you can see how many trust points you have if you look on your bio page, in the Stats box on the top-right of the page.
You can vote a trust point for yourself! Which means you can vote without any reason. And there is no reason that someone can't vote for a friend whether they have answered a question or not.
If you mean you've had an email that says 'You've been recommended' - it simply means that someone found your contribution interesting, stimulating or funny enough to award you a 'trust point'. Your trust points will show on the right of your profile - in the 'Stats' box - and also next to your username when you answer a question. Remember, though trust points are not an indication of the accuracy of an answer !
It means that you added a "trust point". It means that you have recommended someone.