I will say I didn't read everything through thoroughly, but I did have some thoughts.

1) You can't compare this site to just any other SE community. Most of them are targeted at a topic the covers amateurs to professionals. The only other SE site I am familiar with that is targeted purely at professionals while other sites cover the amateur community is SF. That is what we should compare to most often, not just any other SE site.

2) Many SE sites have a few users that answer everything on some given topics. As this is a rather specific site, it isn't unexpected for a user with more time and a willingness to contribute will answer lots of questions here. That is NOT a bad thing.

3) Just because someone else answered the question already does not mean you can't post your own answer, even if it is essentially the same. You may provide a different viewpoint, they way you word things may be clearer to other users, you may have different/better examples, etc. Let the community, OP and future visitors decide which is best for them. I know I have answers where my vote count is higher than the accepted answer or my accepted answer has fewer votes than other answers. That is OK.

4) There is nothing wrong with a user who posts only answers. Why is that such a big deal? They are still contributing to the community in their own way. Do you care if someone gets all their rep by only editing other posts? Let people contribute in their own way.

5) If you don't like someone's answers, please feel free to not vote it up. If you feel strongly about it, then vote it down. Feel free to leave comments with constructive feedback they can use to improve their questions. Just because the answer isn't the best doesn't mean it won't be useful for someone. When I search a SE site, fairly frequently it is one of the lower scored answers that is more helpful to me.

6) When I do ask a question on an SE site, I prefer an answer sooner rather than waiting. Is someone really suggesting that a person with the answer should not provide it just in case someone else may come along to provide the answer later? That really seems foolish to me and counter productive to the needs of those asking questions. Yes it is an archive for future people as well, but the OP deserves an answer if we can provide it.

7) If someone posts a shorter answer and you take the time to provide a longer, better thought out answer, I tend to vote for the longer/better thought out answer. Often to busy to do much voting, but I don't look at time stamps when I do.