Is Yahoo willing to fix the problems in Answers?

Many of these can not be done for several reasons. Here are comments based on your list.

1. Stop askers from answering their own question. (Use Update or Comment.)
1c. This was actually requested by users long ago, good idea or not.

2. Stop askers for posting "thumbs up" on their own question.
2c. This was also requested to prevent users from just doing it anyway from a second account.

3. Require any "thumbs down" post to require an explanatory comment.
3c. Would "I disagree with you" really help. That would be the reason 90% of the time.

4. Require askers to choose a Best Answer before posting another question.
4c. That would drive users away, especially now that questions are open forever.

5. Bring back the search tool for open questions by keyword or phrase.
5c. They really have messed up the searches and sort. No argument here.

6. Banish deliberate repeat offenders (TOS violations).
6c. There is just no way to do this. They can not ban IP addresses so repeat offenders would just use false names and most know how to fool an IP ban anyway. If you have an idea how to ban them, post it on the Suggestion Board.

With the exception of number 6, those are all new features they added, not a problem. They probably won't fix them.

But I agree with addressing the issue about members failing to choose a best answer. I also think they should have the option of choosing "No best answer."

And I think members should be banned from posted ANY links until they reach level 2.

Also, I think that we should have "negative points." Right now, once a member reaches zero points, he cannot have any further deductions. Having negative points would make life harder for the rate-me spammers because they would be unable to post any further questions until they earned at least five points.

Well, I'll disagree on your #4.

My second-to-most recent question only attracted a single answer, and it was a smart-azz answer. Not bad enough to report as abuse, but I'm certainly not going to give it a BA, either.