New deferred lighting path vs the legacy one

Hi !

I was playing around with the Stealth project (I know that it is just for 4.X, but I want the main principles) and in the first assignment, when I choose the deferred lighting path instead of the legacy one everything becomes white or grey !

I have another question (I know it isn't included in the title) and it's where are all the customization options for the fog ? I use global fog and I know that the options are in the lighting window, but there other options which were available in 4.X and aren't available now !

Thanks in Advance