What can I do at PIX-Match and how?

What does the voting and to vote mean at PIX-Match?

Why should I register at PIX-Match?

Why are some categories written in blue, some in orange and some in black?

Why do some PIX disappear from my watch list?

Why is there a stop sign on my site and not the PIX I uploaded?

Why doesn't my PIX take part in the voting immediately after I uploaded and enabled it?

My PIX has won often, why is it still in the rear places?