Usually, the system chooses up to three suitable categories - based on the wording of the question.
Not yet, but if you would like to have it added, you can talk about reasons to add it in the Discussion Page of this question.
Simply by selecting the Miscellaneous category when submitting a question.
If a question is redirected to "What questions add no value to WikiAnswers?", then it became an alternate to that question because it added no value. Questions like "Purple blue yellow ice cream?" will be merged into "What questions add no value to WikiAnswers?" because, as the question states, they do not add any value to the site.
Ask question the answer!
Use your browsers 'Bookmark' option. I use Google Chrome - and created a bookmark for WikiAnswers - with each category listed in order.
You cannot do this on WikiAnswers.
Click the question. Click "Answer question", or "Improve answer", or "Edit". Answer the question and click Save.
Yes. The question mark is added onto the end of the questions you ask, whether you add it yourself or not.
Click discuss question. Then add any extra text into the discussion area.
You can only add photos on your user profile. You cannot add a photo in a question; in an answer; or on the message boards.(See the Related question below.)
Anti-Contributing to WikiAnswersTo add an alternate to a question without counting it as a contribution point, then ask a question on WikiAnswers. Before you officially submit the question, you can edit it. After you edit and submit it, your pre-edited question will be one of its alternates.
You can use the Discuss option on the left hand menu bar, to add more detail to the question.