Attached Link: http://www.renderosity.com/viewed.ez?galleryid=270531&Start=1&Artist=mboncher&ByArtist=Yes

For question 3, you can look at my October Challenge entry "Rapids" for that. I created a sphere and used one of the many cloud presets. Then I multireplicated about 40 of them, and use the 3d scatter to randomly change size and location. After that was done, I arranged them around the rapids till they looked fairly real like spray and mist. If you want shrouded spray, do the same thing but add a second set of spheres low to the bottom with the "star map" preset material or something like that to give the impression of water droplets. Tweek materials as required.