confused by your questions. read what on the internet? what do you mean by witchcraft being 'so important'?
spells to make it rain, you're asking for a grey area in the magick community. the ability to control the weather has be argued for a long time. some say yes because it's nature and energy, while others say no because controlling the weather is too much power for a mortal to have. [plus you can't do things like make it snow in the desert] personally i'm on the fence. if it can be done, it is very hard and shouldn't be cast unless for a life or death situation. the reason why it would be hard is you're controlling weather patterns, not a single cloud. second since you're controlling a weather pattern, the sunny day has to go somewhere, and it could go somewhere where it causes a drought, or your area could flood. if you think about shaman/medicine men tales, there's stories of rain dances in different cultures, but it was used when they were dying, not because they wanted a nice little drizzle. if controlling the weather can be done, i feel it would be abused by people.