I have some shiny pokemon that I want to evolve but want to keep them shiny, how can I do this?
A shiny Pokemon will stay shiny forever, unless your cartridge is tampered with, eg. an Action Reply device or something similar could mess this up.
Yes, it will. If you want to test it out, save your game, evolve the shiny pokemon, if they're not shiny, turn the game off and they will no longer be evolved when you turn it back on. If they are still shny, continue your game and save.
All shiny pokemon will stay shiny even if it evolves.