when you get into sunnyshore go to the small "beach" north of town and talk to the girl/woman, and she will give it to you! the woman should be jasmine. the steel gym leader of the old Johto league. she's pretty and smart =]
Pokemon shiny gold can be only be played on the computer
fire red cheats do not work on Pokemon shiny gold
You get waterfall (HM07) in the Ice Path after Mahogany Town.
to get the HM waterfall defeat the 8th gym leader and talk to the ancient Greek looking lady(before going i would save) she gives you waterfall.
Literally anywhere you see water. Use a fishing rod to catch one. There all over the place! XD -Chii