What is need to lower a truck?

OK, i am lowering my truck and puttin it on bags. what is need in the front and back to lower a truck about 4-5"s and about when do u need to cut ur chis when lowering(how many inches) and with airbags do u need leafsprings. anything will help but i have alot of questions and if any1 would want to give the time to talk about it email me or what ever is needed to do that. thanks