as for night rain shoots....try this!
get 1 or 2 --- i use 1---- floodlights.
what ya do - least this is what i do - get 2 tripods...put ur camera on one..duh...and put a flood light on it. If u use 2 use 3 tripods...3 - 4 tripods...and so on. anyway, find the location u are shooting. get ur light and put it up HIGH.. VERY HIGH. and face it down towards the action. dont put it dead on, put it so there is just enough light to see things on camera. put it BEHIND the action if u can. sometimes u might want it infront, but be careful about that.
anyway, spray the hose nozzle in the air. try not to shoot it up too high, just a foot over the camera range so that was the drops are larger and viewable on camera.
there ya go. hope this sorta helps...donno if u wanted night stuff, but there ya go. also, this is thing NOT to do in a day-for-night thing. the adjusting will prob. make the rain disapear.
Hope this helps ya! I would post some tests, but my camera is in the shop.
Whew.... hope u understand some of this.
PS: u could always do a rain dance...and GET IT ON FILM so we can all see....
also, i would suggest looking at the Batman Dead End movie. it has good night rain scenes. If u look closly the rain doesnt fall on everything....