Peace Rifat,
In my personal opinion, it is healthy to doubt, because that will cause you to verify things and gain more knowledge.
Where you'll end up... only The God knows where.
About your questions lewdness and being a believer...
I would say that the answers to those questions would be very personal to you.
But the main idea on how to find the answers are still the same -- reflect upon yourselves of what you read from the qur'an to your life experiences.
For example, "taqwa". I don't know how you understand this word currently, but I understand it more of "being aware/conscious of <something>" rather than "being righteous". Thus, 22 for me is talking about those who are aware, and only through this awareness they can gain guidance. So to avoid "lewdness" for example, I just try to be aware when I am in lewd-mode ;D (what triggerred it, what have I done during this lewd-mode, is it beneficial to me, etc). Reflect on these questions while reading the qur'an, I'll get my answers regarding "how to avoid lewdness".
As for "believer", I understand it more of those who can uphold the trust/"amanah" given to them, not just those who believe in something. Surah 70 and 90 for example, contain something about the "what" and "how to" of this question.
=adley=