Hello.

There is no "best film speed". Film in Lux doesn't have grain. Exposure is defined by all three elements (film speed, shutter speed and aperture) , we cannot isolate one element alone. It's exactly the same of using a camera.

About 3., that is not noise, it's overblown highlights. About the results, yes, the image is not lit in the most flattering way, the metal material is not set properly and the image is overexposed.

I don't know what lights were used, but if there are spots of, god forbid, distant lights, then the result will not be very flattering. Lighting does the magic. If you look at some of Callads render you will see in fact how the careful use of mesh lights gives a very flattering result. Spots and D.L. should be avoided with Lux. They are unflattering in real life and the result will reflect that physical property. If you use a single mesh light you generally get a much more pleasant result.

Hope this helps.

 

Paolo

https://www.preta3d.com
FB: https://www.facebook.com/RealityPlugIn
Tw: @preta3d
G+: https://plus.google.com/106625816153304163119
The Reality Gallery: https://reality-plug-in.deviantart.com