Great to hear that SimScale platform proves to be useful for you.
Thank you for the suggestions- our development team is working on improving the viewer / post-processor and will get these topics on their agenda.
Regarding the flux calculation, you can already do that when using Result Control Item -> Area Integral over a given surface. As far as I recall, in OF at external boundaries phi is equivalent with U * A.
Regarding the area of the surface- this indeed could be included. At the moment you can do that in ParaView:
Select the face you are interested in (ExtracBlock, etc), use MeshQuality filter with Area as parameter, them IntegrateVariables. This way you obtain the area of the meshed face.
Hope this helps a bit!