What I do is right click the results and ‘add results to the viewer’ then you get two identical solutions. Hide the external mesh for one (thus leaving whatever it is in the middle visible) and then add the streamlines to the other solution. Is that what you want to do? so it will look like the streamlines are actually moving around the object within.
Force coefficients and forces need to be added as a result control item before the simulation is run. You will need to select the faces in which to apply the calculation. For example, if working with an aerofoil then selecting upper and lower surfaces.
Hope this helps,