As far as looking around unnecessarily, it is a deficiency in the salaah of the worshipper as long as he has not turned his entire body in another direction [i.e. away from the Qiblah]. If however the entire body is turned then the salaah is invalidated. It is narrated by ‘Aisha (radiallahu ‘anhaa) who said: I asked the Messenger of Allah (sallallahu ‘alaihi wa sallam) about looking around in the salaah. He said: It is misappropriation pilfered by Shaitaan from the salaah of the worshipper. [Al-Bukhaari]. At-Tirmidhi also collected an authentic hadeeth: Be warned of turning or looking around in the salaah because it is destruction. And there are other ahadeeth on looking around in the salaah.
