Yahoo Q & A answering parsing

[yogeswarl]

Hello Dr.@hosseinfani ,
I am in the process of writing the parser for Yahoo Q & A.
I have the base idea written out and it works well on the sample.
Before I run it on the whole dataset, I would like to clarify a few things on choosing the write content and numbers.

Here is a typical example of a document instance:

<document type="wisdom">
<uri>432470</uri>
<subject>Why are yawns contagious?</subject>
<content>When people yawn, you see that other people in the room yawn, too.  Why is that?</content>
<bestanswer>When your body need more oxygen, you yawn.  &lt;br /&gt;&#xa;When you yawn, you take more oxygen in the air.  &lt;br /&gt;&#xa;If the density of the oxygen in the air becomes lower, other people (their bodies) can feel that and start to yawn to get more oxygen.&lt;br /&gt;&#xa;That's why yawns are contagious. Yawning is extremely contagious -- 55% of people who witness someone yawn will yawn within five minutes. If a visually impaired person hears a tape of someone yawning, he or she is likely to yawn as well. Face it, the likelihood of you making it to the end of this answer without looking like one of these gaping maws is unlikely. &lt;br /&gt;&#xa;Although the contagious nature of yawning is well established, we know less about why this is so. Researchers are currently giving the topic some serious attention. One theory suggests it's a holdover from a period in evolutionary history when yawning served to coordinate the social behavior of a group of animals. A recent study postulates that contagious yawning could be part of the "neural network involved in empathy." &lt;br /&gt;&#xa;&lt;br /&gt;&#xa;While the mystery of contagious yawning has yet to be solved, perhaps researchers are closing in on an answer. On the other hand, given the subject matter, we wouldn't blame them for falling asleep at the wheel. In the meantime, give the "yawn challenge" a try -- it's tougher than it looks.</bestanswer>
<nbestanswers><answer_item>Yawning is extremely contagious -- 55% of people who witness someone yawn will yawn within five minutes. If a visually impaired person hears a tape of someone yawning, he or she is likely to yawn as well. Face it, the likelihood of you making it to the end of this answer without looking like one of these gaping maws is unlikely. &lt;br /&gt;&#xa;Although the contagious nature of yawning is well established, we know less about why this is so. Researchers are currently giving the topic some serious attention. One theory suggests it's a holdover from a period in evolutionary history when yawning served to coordinate the social behavior of a group of animals. A recent study postulates that contagious yawning could be part of the "neural network involved in empathy." &lt;br /&gt;&#xa;&lt;br /&gt;&#xa;While the mystery of contagious yawning has yet to be solved, perhaps researchers are closing in on an answer. On the other hand, given the subject matter, we wouldn't blame them for falling asleep at the wheel. In the meantime, give the "yawn challenge" a try -- it's tougher than it looks.</answer_item>
<answer_item>When your body need more oxygen, you yawn.  &lt;br /&gt;&#xa;When you yawn, you take more oxygen in the air.  &lt;br /&gt;&#xa;If the density of the oxygen in the air becomes lower, other people (their bodies) can feel that and start to yawn to get more oxygen.&lt;br /&gt;&#xa;That's why yawns are contagious.</answer_item>
</nbestanswers>
<cat>Trivia</cat>
<maincat>Education &amp; Reference</maincat>
<subcat>Trivia</subcat>
<date>1127631600</date>
<res_date>1120237002</res_date>
<vot_date>1127977920</vot_date>
<lastanswerts>1161068399</lastanswerts>
<qlang>en</qlang>
<qintl>us</qintl>
<language>en-us</language>
<id>u1254780</id>
<best_id>u1305446</best_id>
</document>

Questions:

1. What is the best one to choose a query. (subject tag or content tag)
2. From the looks of it <bestanswer> is mostly 1 item from <nbestanswers> but sometimes it's a combination of all. What should I do here.?
3. For other works that are extensions of Repair (category, time, e.t.c) what would you like me to extract and store using this parser?
4. My first assumption was <best_id> and <id> would be unique, but some users have answered multiple questions. So what could possibly considered as DID. Also I don't understand what could possibly be the difference between these 2 id's
5. Final and Important!! - For user context, what should I even consider as userID

Confirmed items:

1. the uri tag is going to be queryid