1: Vulkan will unload the cpu a little by preloading shaders/textures in the gpu vram prior to draw calls . This will improve cpu frametimes , but not necessarily fps . This at the expense of using more gpu vram .
3: it will certainly offer a smoother experience , but may or may not provde better fps .
4: not really . Too many variables and individual preferences to make a blanket recommendation . Do your research bearing in mind your ipd , whether you will use the headset for other than seated simming , price point , comfort etc .
5: who knows?
6: SLI is dead ., and if it weren't , DCS VR cannot make use of it anyway .