If I want to ask something that I already know (albeit partially, assume I want to know better answer), is it wise to ask it and answered it, on which the answer is supposed to be the baseline and also to explain the original idea of what would be the solution? Or should I included that detail on the question, although it might limits the opportunity to obtain better answer not constrained by the original concept?
The guiding principle for whether to self-answer or to include previous efforts in the question itself should generally be whether you would upvote and/or accept the answer that you give, if it came from someone else. Self-answers should not receive a free pass, and in fact are often judged more harshly by the community than those posted by people other than the OP. There is nothing wrong with posting a self-answer (in fact, it's even encouraged) as long as it actually answers the question as asked.
That largely answers your question above; if you already have an answer and are seeking more, then your answer can be a candidate for a self-answer to the question. If you have thought about the question, came up with portions of an answer and want others to help flesh out the details in some particular aspect, then it's generally better to describe in the question what you have thought of so far. You can still leave the question open to alternative approaches, perhaps as simply as by writing (in the question, alongside with your thoughts on the matter) something like "this is what I have thought of, but I am open to other suggestions as well". Be careful to not make the question too broad or an idea generation one; for one thing, make sure to state your constraints clearly to avoid this.