sorry, these questions have probably been asked a million times but I haven't found the answers

a) the HDR images dont show in the viewport, and are black there, is that normal? they render fine, and are mapped correctly

b) to reduce noise when they are used for lightning I blur them, I believe the noise comes from rays that are headed in slightly diferent directions, sampling different pixels in the image with differing values, and a blurred image prevents that these pixels values differ too much (correct?)

how can I use the blurred image for lightening only and the unblurred original image to show in the camera directly?

c) GI with images doesnt produce specular effects, you need a light for them therefore you have to place an auxiliary light. any tricks to place the light at the right spot?

d) when there is no light or only dim light or light that only has specular componant in the scene, everythings is near black, how do you quickly switch a bunch of lights on and of without having to switch every light individually?

thanks