Is it taboo to answer my own questions to ...
You are allowed to ask questions and answer them yourself. It is a good thing. I have answered a few of mine own. It is very important that if you do this that you write a good question.
to promote nice features of app?
I am going to disagree with the crowd here and suggest I don't really care about the promotion aspect that much as long as the question is actually good, on topic, and not extremely specific so that it only applies to a very specific situation.
If you can ask a good question, then people will probably up vote it and accept it on the site. If you ask a poor question, and use a good answer that you post as an excuse to ask it, then it will probably be down-voted or closed.
So, ask a question good on-topic question that is as generic as possible, and doesn't have any arbitrary limitation so that only your answer would apply. Leave it open for a while before you post your answer.
We like good questions, and we like good answers. We don't like extremely contrived questions that are only asked so you can promote something.
If you are posting crap, then I will down-vote it, flag it, or vote to close it.