Probably because not enough WikiAnswers contributors have read your contributions or have considered giving you or others a trust point.
I suspect that Supervisors are more likely to attract trust points than other contributors because of the improvements they make to the contributions of others which are likely to then attract a response from the original contributor.
At this point, you can only add Trust Points, not deduct them. So, you can not lost Trust Points.
You can only recommend another contributor once because you already trust them - you shouldn't need to trust them more than you already do. This is also because it is to combat vandalism in Trust Points, as you can get a friend to trust you thousands of times so you can get thousands of trust points, and that isn't how you should earn trust points. Thus, only one recommendation per contributor.
The editing of question and answer material counts as contributions even though they are not obvious and are not subject to the accumulation of trust points. Trust points are given by users who typically will like a question, or like the way a question is answered. This doesn't guarantee that the one who contributed the bulk of the answer will get the trust point. So a person who contributes a lot of time editing/correcting questions and answers will accumulate a large number of contributions without necessarily doing things that might earn points from users. The trust points don't really mean anything though, so you don't have to worry about it.
Many contributors have zero trust points, so it would be very tedious to find and list them all.
I dont think so
There is no maximum amount of trust points one can have on WikiAnswers. At present, the highest amount so far is well over 8,000.(For a list of users with the most trust points, see the Related question)
Trust points are given by other readers of the site. If you write informative, accurate and useful answers, then more people are likely to give you a trust point. Some categories seem to generate more trust points than others so getting a lot of points should never be your sole or most important aim here. Just keep writing useful answers and the points will follow.
Other registered contributors who like your contributions and think they are helpful. You are unable to find out who gives you the Trust Points, unless they message you to say so.
As of now, there is no way to see who gave you the trust points. So, unless the person who gave you the trust point left a message to this effect on your message board, there is no way of knowing.
Any answer that is well-structured, has good grammar and spelling and generally answers the question will earn you trust points. However it is important to remember that some categories have a lot more traffic than other categories, therefore those categories will have more people giving trust points. If you click the recommend question button on the question's answer, the question will appear higher on the main category page which is likely to get your answer more views.
That is more up to your decision. If you look at the username or ID that answers the question, it would show the amount of trust points (ID's do not have trust points, so trusting them is more of a last resort). When you look at the username, the higher the number is of trust points, the more reliable the answer is.
At the bottom of the page.