Panoramas go behind the map. So, for an inside map if you were to make the windows transparent (as you did with your castle
) you could have a panorama that would show through. For outsides, they're only good for edges (where the land/water ends.) This needs to be a place that you can go no farther - a mountain edge, say. It doesn't make sense to artificially use a panorama on a grassland map!
Tone colors depend on the map as well as the shades you like and the mood you're going for. You wouldn't use the same daylight tone in the desert as you would on a snow map! Generally speaking, though, night tones are a lot of grey and blue and not much else, and dawn tones are no grey but a lot of light and green (so push all the colors up a bit and push green just farther than that). Play with it - you'll get what you like eventually.
Fogs are also personal preference - though I typically just use the very first one. Use the X and Y sliders on the lower right of the event window to change how it moves. A higher number makes it move faster. Mess with the opacity and blending for how present it'l be. In addition,they're pretty self explanatory - clouds, leaves, water, fog/smog. I advise against using the leaves one, though.
I assume you know that you can change all these in an event using "change screen color tone" and "Change map settings."