You cannot add whipped cream when the liquid is hot so give time for it to cool off.
When it cools the liquid will be lightly set but it is okay we can whisk it well later when we are going to add the whipped cream.
You can set the mousse for 3-4 hours and serve cool with some chopped badam,pista or any nuts.
For left over whipping cream I have used piping bag to pipe into the glass making layers with mousse(mousse one layer and the cream).
If you are having long glass can set more layers.
Generally mousse are not like pudding the texture is smooth,airy and light.