Purdah

Dressing of a woman when coming before other women

Q: To what extent do women have to lower their gaze with and towards other women if they do (when there’s no fitnah)? I know that you can’t see from below the navel to the knee and including the knees, back and stomach. 

Now in a normal setting among other women, everyone is fully covered but not always in “modest” clothing since it’s females. So in some areas clothes are tight like when wearing a t-shirt for example or trousers. When they wear clothes like this for example, the shape of their body is shown. Are we sinful if we look at their body? Or if we see the shape of things that are apparent or showing (when there is no fitnah)?

Are we supposed to be lowering our gaze as females to other females too? Because when they move etc. even then things naturally show, so what do we do? Are we sinful if we’ve looked or if we’ve seen anything? 

Making salaam or saying Alhamdulillah to a sneeze when a portion of the satr area is exposed

Q: If a man is wearing shorts and his knee and a portion above his knee is exposed. Can such a person greet? As they are saying the name of Allah while their 'awrah is exposed? 

And what is the ruling regarding saying alhamdulillāh after sneezing when one is dressed in a similar manner? Is it makruh or more serious?